Last Updated: August 19, 2026
Use this guide to fix software problems on the Infinix Hot S X521 with official Infinix Hot S X521 firmware. This page contains the necessary flash files, drivers, and step-by-step instructions to resolve bootloops, FRP locks, and other errors.
Device: Infinix Hot S X521 | Chipset: MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU) | Flash Tool: SP Flash Tool
Android: Android 6.0 Marshmallow (XOS) | 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 Hot S X521 (MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU))
Flash Tool: SP Flash Tool
Latest Build: V140
Firmware Files: 7 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 Hot S X521 Firmware (Flash File) Drivers, Tools & Guide
The Infinix Hot S X521 is a device I see frequently with bootloop issues, FRP locks, or problems stuck on the logo. This guide covers everything needed to fix these issues: the firmware, tools, and the process I use. One thing I recommend: extract the firmware to a simple folder path like C:FirmwareX521. SP Flash Tool can sometimes struggle to locate the scatter file if the folder contains spaces or special characters. It is a small detail, but it saves a frustrating few minutes.
This page lists 7 firmware builds for the Infinix Hot S X521, covering multiple Android versions and security patch levels. The device originally released in 2016. The stock firmware ships with Android 6.0 Marshmallow (XOS), which sets the default apps and security features you will see after flashing. With 7 firmware versions archived, this page covers multiple Android builds and security patch levels. As a Transsion Holdings brand, Infinix devices share similar chipset architectures and flashing procedures across the Hot S lineup.
Your Infinix Hot S X521 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. A full flash will erase everything on the device: apps, accounts, photos, and settings. That is the point, it gives you a clean slate and resolves issues like screen locks, FRP prompts, dead boot states, sluggish performance, and connectivity problems.
Factory Reset Infinix Hot S X521 Without a PC
To factory reset the Infinix Hot S X521 without a computer, power off the device completely and hold Volume Up and Power simultaneously until the recovery menu appears.
A hard reset erases all data and restores the Infinix Hot S X521 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 Hot S X521
The fastest method to bypass the Google lock on the Infinix Hot S X521 involves using a free Android apps launcher to access settings during the setup wizard. After flashing or performing a factory reset you may see a Google account lock (FRP). The free Android apps launcher provided is the quickest way to get past it. This is also why I always recommend removing your Google account before flashing, it avoids this problem entirely.
Common Reasons to Reinstall Infinix Hot S X521 Firmware
Reinstalling the stock firmware on the Infinix Hot S X521 resolves various software issues caused by the MediaTek chipset. SP Flash Tool is the standard method for firmware recovery on MTK devices. Here is what flashing the stock firmware can help with:
- Unlock your device if it has been locked or disabled.
- Fix Wi-Fi, Bluetooth, or mobile data connectivity that stopped working after an update.
- Recover your device when it only boots into recovery mode.
- Resolve OTA update failures and battery drain issues.
- Restore system apps that were accidentally removed or corrupted.
- 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.
Which Firmware Version Does Your Infinix Hot S X521 Need?
Before downloading anything, verify your exact device identity to avoid flashing the wrong file.
- Check About Phone: Open Settings and find your exact model number. It should read “X521”, not a similar name, the exact code.
- Match the Chipset: This firmware is built for MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU). If your device has a different processor, it will not flash correctly.
- Look at the Build Number: The build string in your current software should reference the Hot S line. Cross-check it with the firmware table below.
- Check Recovery Mode: Power off, hold Volume Up + Power until recovery appears. The screen displays your chipset and current build, use this to confirm.
- Compare File Details: Make sure the version listed in the download table matches what you expect for your device and region.
Firmware Details for Infinix Hot S X521
Here is a quick overview of the official firmware specifications:
| Firmware Information | Details |
|---|---|
| Device Model | Infinix Hot S X521 |
| Firmware Version | V140, V64, V7, V89, V118, V20 |
| File Size | 1.6 GB to 1.68 GB |
| Android Version | Android 6.0 Marshmallow (XOS) |
| Platform | MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU) |
| Release Date | Released 2016, June |
| 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?
Use this table to determine which firmware version is best for your specific situation.
| Your Situation | What I Recommend |
|---|---|
| Phone is completely dead or stuck on logo | V140, download this one. It is the latest Infinix Hot S X521 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 V118, sometimes the latest OTA introduces new bugs and an older build runs better. |
| IMEI missing after a previous flash | Re-flash V140 first, then follow the IMEI repair guide. Do not skip the reflash. |
| V140 failed with a flash error | Try V118 instead and double-check your scatter file selection before assuming the firmware is the problem. |
| Restoring to factory / warranty repair | V140, 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 Hot S X521 Firmware
Download the official stock firmware for your Infinix Hot S X521 below. The latest available version is V140. 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_X521_MT6735_V140_161223.zip Size: 1.6 GB | Download Link | Download Link2 |
| File Name: Infinix_X521_MT6735_6.0_J5088A1_M.zip Size: 1.68 GB | Download Link | Download Link2 |
| File Name: X521-J5086D1-M-161202V64 Size: 1.65 GB | Download Link | Download Link2 |
| File Name: X521-J5086H1-M-161202V7 Size: 1.65 GB | Download Link | Download Link2 |
| File Name: X521-J5088C1-M-160929V89 Size: 1.65 GB | Download Link | Download Link2 |
| File Name: X521-J5088C1-M-161228V118 Size: 1.61 GB | Download Link | Download Link2 |
| File Name: X521-J5088G1-M-161229V20 Size: 1.64 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 Hot S X521 (X521) should not be confused with other Hot S variants that may have different chipsets or regional firmware. Even devices in the same Hot S line can use completely different processors. Always verify your exact model code “X521” in Settings > About Phone before downloading any firmware from this page.
- Confirm your exact model is X521, check About Phone, not the marketing name on the box.
- Your device must have a MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU) chipset. Boot into recovery mode to verify if unsure.
- Only use files downloaded from this page. Third-party mirrors may serve modified or incomplete packages.
- Compare the file size against the download table. If it does not match, the download is likely corrupt or incomplete.
Prerequisites for Infinix Hot S X521 Firmware
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 Hot S X521 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.
- Record IMEI Before Flashing: Dial *#06# and save both IMEI numbers somewhere safe, a screenshot works. If flashing corrupts the baseband, these numbers are what you will need to restore cellular connectivity.
- Unlink Google Accounts: Go to Settings, then Accounts, and remove all Google accounts. This prevents Factory Reset Protection from activating after the flash. It is the single most skipped step and causes the most post-flash headaches.
- Full Data Backup: Flashing erases everything. Transfer your photos, contacts, app data, and any important files to your computer or cloud backup before starting.
- Charge the Battery: Make sure you have at least 50% charge. A dead battery during a flash can corrupt the system partition and turn a fixable problem into a much bigger one.
- Windows PC and USB Cable: You will need a Windows computer and a data-capable USB cable. Cheap charge-only cables are the number one reason flash tools fail to detect devices.
- Driver Installation:
Flashing Infinix Hot S X521 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 Extract:
- Download the correct firmware package from the links above.
- Extract the ZIP to a simple folder path, avoid paths with spaces or special characters, as some flash tools have trouble with them.
- Install the Listed Drivers:
- Confirm all drivers listed above are installed and that your PC has been restarted since installation. Skipping the restart is a common reason drivers do not work correctly.
- 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:
- Click the “Download” button to begin.
- Do not disconnect, move the cable, or touch the device until the process is fully complete. Disconnecting mid-flash is how devices get bricked.
- Wait and Reboot:
- Once flashing finishes successfully, disconnect the device.
- Power on your device. The first boot will take longer than usual, give it up to 8 minutes.
Normal Behavior After Installing Infinix Hot S X521 Firmware
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.
- Battery percentage may seem inaccurate for the first day. The battery statistics are calibrated during normal use. Charge the phone fully once without interruption and the readings will stabilize.
- The phone may ask for language and region again, this is normal after a flash. You are starting from a clean state, so the setup wizard runs just like when the phone was brand new.
- The phone will feel warm during first boot, this is normal. It settles after a few minutes once the initial app setup is complete.
- 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.
- 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.
- Dial *#06# immediately after setup to check your IMEI. Do this before you insert a SIM card. If it shows “unknown” or “null”, follow the IMEI repair guide below before doing anything else.
Infinix Hot S X521 Flashing Problems and Fixes
- Infinix Hot S X521 Not Recognized by SP Flash Tool:
- In most cases this is a driver issue, not a cable issue. Reinstall the VCOM drivers for the X521, 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 Hot S X521 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: Can I go back to an older firmware version?
A: It is technically possible on some MediaTek builds, but downgrading can cause security issues and app compatibility problems. If the latest version is causing trouble, leave a comment below, there is usually a better fix than rolling back.
Q2: Can I flash this firmware if my phone does not turn on at all?
A: Yes, in most cases. As long as the phone responds to a USB connection (even with a black screen), the flash tool can detect it. If the battery is completely drained, charge it for at least 15 minutes first.
Q3: 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.
Q4: 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.
Q5: Will flashing erase my data?
A: Yes, flashing with SP Flash Tool restores the device to factory state, including Android 6.0 Marshmallow (XOS) 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.
Q6: My device is not detected by SP Flash Tool. What should I do?
A: Start with the drivers, reinstall the VCOM drivers, restart your PC, then try again. Switch to a USB 2.0 port if you are on USB 3.0. Disable your antivirus temporarily. If none of that works, leave a comment with the exact error message.
Q7: Is it safe to flash during a power outage risk?
A: It is best to avoid flashing during unstable power conditions. If your PC shuts down during the flash, it can corrupt the write and leave the phone in an unbootable state. If you are in an area with unreliable power, use a laptop with a fully charged battery instead of a desktop.
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 Hot S X521
What chipset does the Infinix Hot S X521 use?
The Infinix Hot S X521 uses the MediaTek MT6735 (Quad-core 1.5 GHz ARM Cortex-A53, ARM Mali-T720 GPU) 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 Hot S X521 erase my data?
Yes. Flashing stock firmware on the Infinix Hot S X521 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 Hot S X521?
Yes. If your Infinix Hot S X521 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 Hot S X521?
The latest available Infinix Hot S X521 firmware on this page is version V140. This page has 7 firmware builds available for download. Check the firmware details table above for file sizes and Android versions.
Infinix Hot S X521 Firmware, Final Notes
That is everything you need to safely flash the official Infinix Hot S X521 firmware (V140) using SP Flash Tool and get your device working again. If you followed each step, your phone should now be running on a clean build.
If something did not go as expected, a specific error, a step that is not working for your setup, leave a comment below with as much detail as you can: the exact error message, which step you are on, and what you have already tried. I read every comment and will help you work through it.
If this guide helped you, consider sharing it, it is the best way to help someone else who is dealing with the same problem.
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.
