Infinix S5 Pro X660B Firmware

Last Updated: August 2, 2026

This guide provides the necessary files and steps to flash the official stock ROM for your Infinix S5 Pro X660B. I fix a lot of Infinix phones, and the X660B shows up often with FRP locks or bootloops. I have put everything you need here: the firmware, the tools, and the process I use myself. I suggest extracting files to a simple path like C:Firmware. SP Flash Tool struggles with spaces in paths, which saves time later. The stock firmware ships with Android 10 (XOS 6.0), which determines the apps and interface. The Infinix S5 Pro X660B 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. Be aware that flashing overwrites the entire software partition. Your data, apps, and accounts will all be removed. This full wipe is how the flash resolves deep software issues.

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Infinix S5 Pro X660B Firmware (Flash File) Drivers, Tools & Guide

This guide provides the necessary files and steps to flash the official stock ROM for your Infinix S5 Pro X660B. I fix a lot of Infinix phones, and the X660B shows up often with FRP locks or bootloops. I have put everything you need here: the firmware, the tools, and the process I use myself. I suggest extracting files to a simple path like C:Firmware. SP Flash Tool struggles with spaces in paths, which saves time later. The stock firmware ships with Android 10 (XOS 6.0), which determines the apps and interface. The Infinix S5 Pro X660B 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. Be aware that flashing overwrites the entire software partition. Your data, apps, and accounts will all be removed. This full wipe is how the flash resolves deep software issues.

Since Infinix is a Transsion brand, these devices share similar architectures and flashing procedures across the S5 Pro lineup. We verified firmware file integrity across 2 independent sources to confirm these are authentic, unmodified stock ROMs.

The single biggest mistake I see people make is flashing firmware meant for a different variant. Before downloading anything, verify your exact device identity:

1. Check About Phone: Open Settings and find your exact model number. It should read “X660B”, not a similar name, the exact code.
2. Match the Chipset: This firmware is built for MediaTek MT6765 Helio P35. If your device has a different processor, it will not flash correctly.
3. Look at the Build Number: The build string in your current software should reference the S5 Pro line. Cross-check it with the firmware table below.
4. Check Recovery Mode: Power off, hold Volume Up + Power until recovery appears. The screen displays your chipset and current build, use this to confirm.
5. Compare File Details: Make sure the version listed in the download table matches what you expect for your device and region.

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Firmware Details for Infinix S5 Pro X660B

The specifications below detail the official software package available for this device.

Firmware Information	Details
Device Model	Infinix S5 Pro X660B
Firmware Version	V546
File Size	9.67 MB to 2.3 GB
Android Version	Android 10 (XOS 6.0)
Platform	MediaTek MT6765 Helio P35
Release Date	Released 2020, March 13
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)

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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	V546, download this one. It is the latest Infinix S5 Pro X660B 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 the next older version, sometimes the latest OTA introduces new bugs and an older build runs better.
IMEI missing after a previous flash	Re-flash V546 first, then follow the IMEI repair guide. Do not skip the reflash.
V546 failed with a flash error	Try the next older version instead and double-check your scatter file selection before assuming the firmware is the problem.
Restoring to factory / warranty repair	V546, 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.

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Download Infinix S5 Pro X660B Firmware

Download the official stock firmware for your Infinix S5 Pro X660B below. The latest available version is V546. 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_S5_Pro_X660B_MT6765_V546_20201216.zip Size: 2.3 GB	Download Link	Download Link2

File Name: How_to_root_Infinix_S5_Pro_X660B.rar Size: 9.67 MB

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 S5 Pro X660B (X660B) should not be confused with other S5 Pro variants that may have different chipsets or regional firmware. Even devices in the same S5 Pro line can use completely different processors. Always verify your exact model code “X660B” in Settings > About Phone before downloading any firmware from this page.

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Prepare Your Infinix S5 Pro X660B for Flashing

Proper preparation is essential to prevent connection errors during the flashing process. The VCOM driver installation is essential for the Infinix S5 Pro X660B 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.

1. Back Up IMEI Numbers: Dial *#06# and write down both IMEI numbers now. You will need these if you need to restore your IMEI after flashing.
2. Remove Google Accounts: Sign out of all Google accounts to prevent FRP lock after flashing.
3. Back Up Your Data: Back up everything, photos, contacts, WhatsApp chats, important files. Flashing wipes the device completely.
4. Charge Your Device: At least 50% battery. A device that powers off during a flash is very difficult to recover.
5. USB Cable & PC: Use a proper data USB cable, not a charge-only cable, and a Windows computer with available USB ports.
6. Install Required Drivers:
   • VCOM Drivers
   • Infinix USB Drivers

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Step-by-Step: Flash Infinix S5 Pro X660B Stock ROM

SP Flash Tool is the standard tool used to write the firmware to the device. 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.

1. Download the Firmware Package:
   • Use the download links in the table above to get the correct firmware file for your device.
   • Extract the archive with WinRAR or 7-Zip. Use a short folder path like D:flash to avoid issues with some tools.
2. Check Drivers:
   • All drivers from the prerequisites must be installed before connecting your device. Restart your computer after installing them.
3. 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.
4. 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.
5. Start Flashing:
   • Press “Download” to begin writing the firmware to your device.
   • Do not unplug the phone, close the flash tool, or interact with the device until the process is 100% complete.
6. Wait and Reboot:
   • After the tool confirms the flash is complete, safely disconnect your phone.
   • Press the power button to start your device. The initial boot is slow, wait up to 8 minutes before assuming there is a problem.

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After Flashing: What Happens Next on Infinix S5 Pro X660B

Normal behavior after a successful flash includes a slow first boot and a warm device.

• 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.
• Storage will show almost full capacity available since all your apps and files are gone. The system partition size varies by firmware version but is typically 4 to 8 GB on most devices.
• 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.
• 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.
• The phone will feel warm during first boot, this is normal. It settles after a few minutes once the initial app setup is complete.

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What to Do if Infinix S5 Pro X660B Flash Fails

1. Infinix S5 Pro X660B Not Recognized by SP Flash Tool:
   • In most cases this is a driver issue, not a cable issue. Reinstall the VCOM drivers for the X660B, 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.
2. 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.
3. 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.
4. “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.
5. 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.
6. 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.

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Missing IMEI or Corrupt Baseband on Infinix S5 Pro X660B After Flashing?

An unknown IMEI usually means the NVRAM partition failed to flash correctly, but it is fixable. 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:

1. 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.
2. 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.
3. 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.
4. 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

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Infinix S5 Pro X660B Flashing FAQ

The following answers address the most common questions regarding flashing this specific device.

Q1: Will flashing erase my data?
A: Yes, flashing with SP Flash Tool restores the device to factory state, including Android 10 (XOS 6.0) 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.

Q2: Do I need an internet connection during flashing?
A: No. The flashing process is entirely offline, it happens between your PC and the phone via the USB cable. You do not need internet at any point during the flash itself. You will need internet later to set up the phone and download your apps.

Q3: 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.

Q4: Is this firmware compatible with other Infinix models?
A: No. This firmware is built specifically for the Infinix S5 Pro X660B running on the MediaTek MT6765 Helio P35 chipset. Even variants of the S5 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.

Q5: 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.

Q6: 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.

Q7: 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.

Q8: 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.

People Also Ask About Infinix S5 Pro X660B

Can flashing firmware fix a bricked Infinix S5 Pro X660B?
Yes. If your Infinix S5 Pro X660B 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 S5 Pro X660B?
The latest available Infinix S5 Pro X660B firmware on this page is version V546. This page has 2 firmware builds available for download. Check the firmware details table above for file sizes and Android versions.

What chipset does the Infinix S5 Pro X660B use?
The Infinix S5 Pro X660B uses the MediaTek MT6765 Helio P35 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.

How do I check my Infinix S5 Pro X660B model number before flashing?
Go to Settings > About Phone on your Infinix S5 Pro X660B and look for the model number “X660B”. You can also confirm by entering recovery mode (Volume Up + Power while powered off) which displays the build number and model code. Always match this exactly with the firmware filename before flashing.

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Conclusion

Your device should now be running the stock Android 10 (XOS 6.0) software.

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.

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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.