Last Updated: August 14, 2026
If your Infinix Note 40 Pro+ X6851B is stuck on a logo, locked out, or not responding, this guide walks you through the full recovery process with official firmware, the right flash tool, and clear instructions.
Device: Infinix Note 40 Pro+ X6851B | Chipset: MediaTek Dimensity 7020 (MT6855) | Flash Tool: SP Flash Tool
Android: Android 14, XOS 14 | File Type: ZIP (Includes Scatter File [MT6xxx_Android_scatter.txt], preloader.bin, boot.img, system.img, recovery.img, lk.bin, logo.bin, nvram.img, and more)
⚠ Warning: Flashing erases all data. Back up first.
Device: Infinix Note 40 Pro+ X6851B (MediaTek Dimensity 7020 (MT6855))
Flash Tool: SP Flash Tool
Latest Build: V867
Firmware Files: 2 available
What You Need: Windows PC, USB data cable, SP Flash Tool, USB drivers
Time Required: 10-20 minutes (plus 3-8 min first boot)
Infinix Note 40 Pro+ X6851B Firmware (Flash File) Drivers, Tools & Guide
I have worked with Infinix phones for a long time, and the Infinix Note 40 Pro+ X6851B comes in often, usually with FRP locks, bootloop issues, or stuck on the Infinix logo. This guide covers all of it. I have put everything you need in one place: the firmware, the tools, and the exact process I use myself.
One thing I always recommend before you start: extract the firmware to a simple folder path, something like C:FirmwareX6851B. SP Flash Tool can sometimes have trouble locating the scatter file if the folder path contains spaces or special characters. It is a small thing, but it saves a frustrating few minutes of wondering why the tool is not loading the file.
The stock firmware ships with Android 14, XOS 14, which determines the default apps, security features, and interface you will see after flashing. Released in 2024, the Infinix Note 40 Pro+ X6851B has been on the market long enough that multiple firmware builds are available, giving you options if one version causes issues. There are 2 firmware files available for the Infinix Note 40 Pro+ X6851B on this page. Pick the one that matches your current Android version for the smoothest flash.
As a Transsion Holdings brand, Infinix devices share similar chipset architectures and flashing procedures across the Note 40 Pro+ lineup. This firmware was sourced directly from verified repositories and checked for integrity before being listed on this page.
Your Infinix Note 40 Pro+ X6851B firmware comes as a compressed ZIP file. Download and extract it using WinRAR or 7-Zip. Once extracted, open the folder and confirm it contains the scatter file before proceeding.
Keep in mind that flashing stock firmware erases all data, which is intentional, as it resolves software issues including FRP lock, app problems, slow performance, forgotten pattern locks, a dead or logo-stuck device, Wi-Fi and Bluetooth issues, battery drain, and soft brick situations.
How to Wipe Infinix Note 40 Pro+ X6851B to Factory Settings
To factory reset Infinix Note 40 Pro+ X6851B without a computer, power off the device completely, then hold Volume Up and Power at the same time until the recovery menu appears. Use the volume keys to navigate to “Wipe Data/Factory Reset” and confirm with the Power button.
A hard reset erases all data and restores Infinix Note 40 Pro+ X6851B to its original factory state. This fixes most software problems, slow performance, app crashes, forgotten screen locks, and bootloops. If the issue persists after a factory reset, a full firmware flash using SP Flash Tool is covered in the following sections.
Bypass Google Lock on Infinix Note 40 Pro+ X6851B
The fastest way to bypass FRP on Infinix Note 40 Pro+ X6851B is to use a free Android apps launcher that lets you access settings during the setup wizard. After flashing or performing a factory reset you may see a Google account lock (FRP). Our free Android apps launcher is the fastest way to get past it. This is also why I always recommend removing your Google account before flashing, it avoids this problem entirely.
Why Do We Need Infinix Note 40 Pro+ X6851B Firmware?
The Infinix Note 40 Pro+ X6851B firmware is necessary because the device uses a MediaTek chipset, and SP Flash Tool is the standard method for firmware recovery on MTK devices. Here is what flashing the stock firmware can help with:
- Restore system apps that were accidentally removed or corrupted.
- Restore the original Infinix stock ROM to keep your warranty valid.
- Fix Wi-Fi, Bluetooth, or mobile data connectivity that stopped working after an update.
- Unlock your device if it has been locked or disabled.
- Fix startup loops, lagging, and freezing on your device.
- Remove persistent malware or adware that survives a factory reset.
- Recover from “Download DA FAIL” errors and Secure Boot authentication issues specific to the MediaTek chipset in your device.
Learn more about stock ROMs and why flashing works.
Infinix Note 40 Pro+ X6851B Firmware Compatibility Check
The single biggest mistake I see people make is flashing firmware meant for a different variant. Before downloading anything, verify your exact device identity:
- Verify Your Exact Model: In Settings, look for the model code “X6851B”. Some Infinix phones share the same marketing name but have different internal hardware.
- Confirm the Processor: This build targets the MediaTek Dimensity 7020 (MT6855) chipset. You can check your chipset via recovery mode or a hardware info app.
- Review the Version Number: The firmware version in the download table should be close to or newer than what your device is currently running.
- Use Recovery Mode as a Safety Check: Before flashing, boot into recovery to see the current build number and chipset printed on screen. This is the most trustworthy check.
- Verify the Region: Some firmware builds are region-specific. Confirm the download matches your device region or is listed as global.
Firmware Details for Infinix Note 40 Pro+ X6851B
Here is a quick overview of the official firmware specifications:
| Firmware Information | Details |
|---|---|
| Device Model | Infinix Note 40 Pro+ X6851B |
| Firmware Version | 15.0.3.127SP03, V867 |
| File Size | 5.9 GB to 15.4 GB |
| Android Version | Android 14, XOS 14 |
| Platform | MediaTek Dimensity 7020 (MT6855) |
| Release Date | Released 2024, March 19 |
| Region | Global, Africa and Asia |
| File Type | ZIP (Includes Scatter File [MT6xxx_Android_scatter.txt], preloader.bin, boot.img, system.img, recovery.img, lk.bin, logo.bin, nvram.img, and more) |
Which Firmware Version Should I Download?
This is the question I get asked most often in the comments, so I put together a simple guide. Find your situation in the table and go straight to the right file:
| Your Situation | What I Recommend |
|---|---|
| Phone is completely dead or stuck on logo | V867, download this one. It is the latest Infinix Note 40 Pro+ X6851B firmware available. |
| FRP / Google account lock only | See the FRP bypass guide above, you likely do not need the full firmware for this. |
| Phone slow after a recent OTA update | Try 15.0.3.127SP03, sometimes the latest OTA introduces new bugs and an older build runs better. |
| IMEI missing after a previous flash | Re-flash V867 first, then follow the IMEI repair guide. Do not skip the reflash. |
| V867 failed with a flash error | Try 15.0.3.127SP03 instead and double-check your scatter file selection before assuming the firmware is the problem. |
| Restoring to factory / warranty repair | V867, clean state, fresh start. |
My general approach with MTK devices: always try the latest version first. I have seen people spend a lot of time trying older builds when the newest one would have worked fine. Only move to an older version if the latest fails more than once, and make sure it is a driver issue you are solving, not a firmware issue.
Download Infinix Note 40 Pro+ X6851B Firmware
Download the official stock firmware for your Infinix Note 40 Pro+ X6851B below. The latest available version is V867. After downloading, verify the file size matches the table above, a size mismatch usually means a partial or corrupt download, and flashing a corrupt file can cause more problems than it solves.
| Software Details | Download Link | Members Link |
|---|---|---|
|
File Name: Infinix_Note_40_Pro_Plus_5G_X6851B_MT6855_15.0.3.127SP03_OP001PF001AZ_050625_MXML.zip Size: 15.4 GB | Download Link | Download Link2 |
| File Name: X6851B-P865AC-U-IN-240313V867 Factory Signed Firmware.zip Size: 5.9 GB | Download Link | Download Link2 |
Only download firmware that is fully compatible with your exact device model. See the firmware selection guide above if you are not sure.
Important: The Infinix Note 40 Pro+ X6851B (X6851B) should not be confused with other Note 40 Pro+ variants that may have different chipsets or regional firmware. Even devices in the same Note 40 Pro+ line can use completely different processors. Always verify your exact model code “X6851B” in Settings > About Phone before downloading any firmware from this page.
- Your model number is a variant of X6851B with a different letter suffix. Check About Phone carefully, one letter difference can cause a failed or broken flash.
- Your chipset differs from MediaTek Dimensity 7020 (MT6855). Confirm in recovery mode before proceeding.
- You downloaded the file from a source other than this page.
- The file size differs significantly from the sizes listed in the table above, a size mismatch usually means a partial download, which will fail mid-flash.
Prepare Your Infinix Note 40 Pro+ X6851B for Flashing
Do not skip this section. Most failed Infinix flashes come from rushing through the preparation steps. The VCOM driver installation is essential for the Infinix Note 40 Pro+ X6851B and other MediaTek devices. Windows may show the device in Device Manager and SP Flash Tool will still not detect it if the correct VCOM driver is not installed.
- IMEI Backup: Open the dialer and enter *#06#. Write both IMEI numbers down on paper or take a screenshot. If you ever need to repair your IMEI after flashing, these are essential.
- Remove All Google Accounts: Go to Settings, Accounts, and sign out of every Google account on the device. Leaving accounts signed in triggers FRP lock after a flash, which blocks you from setting up the phone.
- Backup Everything: Photos, contacts, messages, WhatsApp data, move it all to a computer or cloud service. The flash will restore the phone to factory state with nothing on it.
- 50% Battery Minimum: Do not start with a low battery. If power cuts out during the flash, the device can become unresponsive and much harder to fix.
- USB Cable and Computer: Use a proper data-transfer USB cable and a Windows PC. Avoid USB hubs, connect directly to the motherboard port for a stable connection.
- Download and Install Drivers:
Flashing Infinix Note 40 Pro+ X6851B Firmware With SP Flash Tool
We are using SP Flash Tool for this. For older devices, I recommend trying SP Flash Tool v5.1924 first. The newer versions of SP Flash Tool require a DA (Download Agent) file that older firmware packages do not include, and that is what causes the “Auth” errors you may have seen. If SP Flash Tool keeps asking for an auth file and you do not have one, switch to MTK Client, it handles Secure Boot automatically. Download SP Flash Tool for Windows or SP Flash Tool for Linux and follow the steps below. The complete SP Flash Tool guide is also available if you need more detail.
- Download and Unpack:
- Pick the correct firmware version from the downloads above and save it to your PC.
- Extract the ZIP file. If the extracted folder contains another ZIP inside, extract that one too. You should end up with the actual firmware files, not another archive.
- Driver Check:
- Double-check that you have installed the required drivers. A missing driver is the most common reason the flash tool cannot detect your phone. Reboot your PC after installing.
- Load the Firmware File:
- Click on the “Scatter-loading” button. Navigate to the folder where you extracted the firmware and select the “scatter.txt” file.
- Connect Your Device:
- Power off your phone completely, not sleep mode, fully off.
- Connect to your PC via USB cable. The flash tool will detect it automatically.
- Start Flashing:
- Start the flash by clicking “Download”.
- Leave everything untouched until completion. Even bumping the USB cable can interrupt the write and cause a failed flash.
- Wait and Reboot:
- The flash is complete when the tool shows a success indicator. Disconnect your phone.
- Turn the phone on. Do not worry if it sits on the boot logo for several minutes, the system is rebuilding itself from scratch.
Post-Flash Behavior on Infinix Note 40 Pro+ X6851B
Here is what is completely normal after a successful flash:
- How to know the flash was successful: SP Flash Tool will show a green circle or checkmark when done. If you see that, the flash completed successfully.
- The phone will feel warm during first boot, this is normal. It settles after a few minutes once the initial app setup is complete.
- Be careful when re-adding your Google account, if you did not remove it before flashing, you may see an FRP prompt. Add it fresh during the setup wizard, not afterwards through Settings.
- Stuck in a bootloop after first boot? Enter recovery mode and do a factory reset from there, see the hard reset guide above. This can happen occasionally and does not mean the firmware is wrong.
- First boot takes 3 to 8 minutes, do not force-reboot the device. The operating system is setting itself up from scratch. Interrupting this is how devices end up in bootloops.
- Fingerprint and face unlock data are erased during the flash. You will need to re-register your fingerprints and face data from scratch in the security settings.
- Notification sounds and ringtones will be back to factory defaults. Any custom tones you had set before will need to be re-downloaded and re-assigned in Settings.
Fix Common Infinix Note 40 Pro+ X6851B Firmware Errors
- Infinix Note 40 Pro+ X6851B Not Recognized by SP Flash Tool:
- In most cases this is a driver issue, not a cable issue. Reinstall the VCOM drivers for the X6851B, restart your PC, and try again before changing anything else.
- If that does not work, switch to a USB 2.0 port, USB 3.0 ports can cause detection issues with MediaTek devices more often than people expect.
- Still not working? Temporarily disable your antivirus. It can block the VCOM driver from loading without giving you any error message.
- Boot Loop After Flashing:
- Enter recovery mode and perform a factory reset from there. Most post-flash bootloops on MediaTek are caused by conflicts with old cached data, a wipe from recovery usually fixes this without needing to reflash.
- Wrong Scatter File / Firmware Mismatch:
- If SP Flash Tool throws an error as soon as you try to start the download, check your scatter file first. A mismatch between the scatter file and your device build is one of the most common causes of flash errors.
- “Download DA FAIL” Error:
- This error comes up regularly. It almost always means the VCOM driver is not properly installed. Reinstall it, restart your PC, and try again. If that still does not work, try switching to SP Flash Tool v5.1924, older devices sometimes respond better to the older version.
- Error 8038 (BROM Error):
- The device is not entering BROM mode correctly. Power it off completely and, if possible, remove the battery for 30 seconds. Reconnect and try again. Some MediaTek devices require you to hold Volume Down while plugging in the USB cable to enter BROM mode.
- Auth File / Secure Boot Error in Newer SP Flash Tool:
- Newer versions of SP Flash Tool require a DA (Download Agent) authentication file for devices with Secure Boot enabled. If you do not have that file, switch to MTK Client instead, it handles Secure Boot automatically and is the simpler solution.
Missing IMEI or Corrupt Baseband on Infinix Note 40 Pro+ X6851B After Flashing?
A missing or unknown IMEI is one of the most common things I see after a MediaTek flash. It happens because the NVRAM partition, which stores your IMEI and calibration data, sometimes does not survive the flash intact. It looks alarming, but it is fixable. Here is what to do:
- Check your drivers first: Install the Mediatek CDC Driver if you have not already, without it, the IMEI repair tools will not detect your device. This is the step most people miss.
- Use SN Write Tool or Maui Meta: SN Write Tool is the first option I try, it is straightforward and works on most MTK devices. Maui Meta is the alternative if SN Write does not connect. You can learn more about using SN Write Tool here.
- Run the repair:
- Connect your device to the computer.
- Enter the original IMEI numbers for both SIM slots, these are the numbers you wrote down before flashing.
- Click “Start” and let it complete without interrupting the connection.
- Verify after reboot: Once done, reboot your phone and dial *#06#. Your IMEI numbers should be back. If they are still showing null, run the process again, sometimes the first attempt does not complete correctly.
Video Guide: How to repair IMEI
Credits: https://www.youtube.com/@mhgsmclinic
Frequently Asked Questions
Q1: Will flashing void my warranty?
A: Flashing official stock firmware generally does not void your warranty since you are restoring the device to its factory-intended state. However, some manufacturers may flag that the bootloader was unlocked or that the flash counter increased. Check your specific warranty terms with Infinix support if you are concerned.
Q2: Is this firmware compatible with other Infinix models?
A: No. This firmware is built specifically for the Infinix Note 40 Pro+ X6851B running on the MediaTek Dimensity 7020 (MT6855) chipset. Even variants of the Note 40 Pro+ with a different letter suffix can have a completely different chipset inside. Flashing the wrong firmware can leave your phone in a state that is very difficult to recover from. Always check your exact model number in Settings.
Q3: Will flashing erase my data?
A: Yes, flashing with SP Flash Tool restores the device to factory state, including Android 14, XOS 14 default settings. All apps, photos, contacts, and accounts will be removed. Back up everything you need before you start. There is no way to recover data once the flash is complete.
Q4: How long does the flashing process take?
A: The actual flash usually takes between 3 and 10 minutes depending on the firmware size and USB connection speed. The first boot after flashing takes another 3 to 8 minutes. Do not interrupt the device during either stage. If the progress bar in SP Flash Tool appears stuck, give it a few more minutes before assuming something went wrong.
Q5: How do I enter recovery mode?
A: Power the device off completely, then hold Volume Up + Power at the same time until the recovery menu appears. The recovery menu displays the build number which you can use to verify your firmware version before flashing.
Q6: What if the flash fails halfway through?
A: Do not panic and do not disconnect the phone. Close SP Flash Tool, restart it, and try the flash again from the beginning. In most cases, a failed flash just means the process needs to be repeated. The device is usually still detectable by the flash tool even after a failed attempt.
Q7: Can I use a Mac or Linux computer for this?
A: The tools and drivers referenced on this page are Windows-only. If you are on Mac or Linux, your best option is to use a Windows virtual machine, or borrow a Windows PC for the 10 minutes it takes to complete the flash.
Q8: My IMEI shows “unknown” after flashing. Is my phone permanently damaged?
A: No, it looks alarming, but it is fixable. Follow the IMEI repair guide in the troubleshooting section above. For MediaTek devices, SN Write Tool or Maui Meta will handle the repair. Do not insert a SIM card until the IMEI is restored.
People Also Ask About Infinix Note 40 Pro+ X6851B
What chipset does the Infinix Note 40 Pro+ X6851B use?
The Infinix Note 40 Pro+ X6851B uses the MediaTek Dimensity 7020 (MT6855) chipset, a MediaTek processor. This means you need SP Flash Tool and VCOM/MTK USB drivers to flash firmware. MediaTek devices use scatter-file-based flashing, which is different from Qualcomm (QFIL) or Samsung (Odin) methods.
Will flashing firmware on Infinix Note 40 Pro+ X6851B erase my data?
Yes. Flashing stock firmware on the Infinix Note 40 Pro+ X6851B with SP Flash Tool performs a full factory reset. All apps, photos, contacts, and accounts will be removed. Back up everything important before you start. There is no way to recover data after flashing.
Can flashing firmware fix a bricked Infinix Note 40 Pro+ X6851B?
Yes. If your Infinix Note 40 Pro+ X6851B is stuck on the logo, in a bootloop, or will not turn on, flashing the stock firmware with SP Flash Tool can restore it to working condition. This is the standard repair method used by service centers for Infinix devices.
What is the latest firmware version for Infinix Note 40 Pro+ X6851B?
The latest available Infinix Note 40 Pro+ X6851B firmware on this page is version V867. This page has 2 firmware builds available for download. Check the firmware details table above for file sizes and Android versions.
Conclusion
The flash is done. Your Infinix Note 40 Pro+ X6851B is back on official stock firmware and should be running without the issues that brought you here.
If anything went differently than described, an error message, a step that did not match your setup, post it in the comments. I respond to every question.
This guide gets updated when new builds are released, so you can come back anytime you need a newer version.
Browse all Infinix firmware downloads for more devices.
Disclaimer: Flashing stock firmware is performed at your own risk. Follow the instructions on this page carefully. I cannot be held responsible for any damage to your device, but I will always try to help if something goes wrong.
