How to flash Xiaomi Redmi 9T: official and custom firmware

Why to Switch Redmi 9T and When to Use It

Xiaomi Redmi 9T (codenamed lime) is still popular years after its release due to its balanced features: Snapdragon 662 processor, 6000 mAh battery and MIUI based on Android. However, over time, owners face slowdowns, system errors or the desire to install a fresh version of Android.

When should you update software? First, if the official updates stopped coming (Xiaomi supports Redmi 9T to MIUI 14 on Android 12, but not all regions receive updates at the same time); Second, when critical bugs — for example, when the smartphone does not save network settings after rebooting (a known problem in some builds of MIUI 13); Third, to install custom firmware like LineageOS or Pixel Experience, which offer “clean” Android without advertising and unnecessary Xiaomi services.

But firmware is not a panacea. If your phone is slowing down because of a full memory or a worn-out battery, software updates won't help. And in the case of hardware breakdowns (like a faulty Wi-Fi module), flashing it can make things worse. Before you act, check if the software is really the problem.

Preparation for firmware: what to do before the start

The Redmi 9T firmware process begins long before you connect your phone to your computer. The first and most important thing is to save all the data. Even if you plan to upgrade without reset (via OTA), there is always a risk of failure. Use Mi Mover (built into the MIUI application) or third-party utilities like Titanium Backup (requires root).

• 📱 Contact (export to) VCF-file)
• 📸 Photos and videos (copy to PC or cloud)
• 🔑 Passwords from apps (write down or use password manager)
• 🎮 Save games (synchronize with your account) Google/Mi)

Second, check the MIUI version and bootloader status. Go to Settings → About Phone → MIUI version. If it says Stable, you have official firmware. You can find out the bootloader status by typing in fastboot mode the command:

fastboot oem device-info

If the answer has a line Device unlocked: true, the bootloader is already unlocked. Otherwise, you will need to unlock (more on this below).

⚠️ Attention: On Redmi 9T global firmware (suffix) EEA or Global) unlocking the bootloader takes up to 7 days to wait (CN) This period may be up to 30 days.

Third, prepare the tools:

Unlocking the bootloader: a mandatory step for custom firmware

The Redmi 9T bootloader is blocked by default, a security measure from Xiaomi that prevents uncertified software from being installed. There is no need to unlock official firmware (via the Mi Flash Tool), but if you want to put custom ROM or get root access, you can’t do without it.

The unlocking process consists of three stages:

1. Link your Mi Account to your device. Go to Settings → Xiaomi Account → Mi Cloud and enable sync. Then to Settings → Additional → Developer → Mi Unlock Status, link your account.
2. Waiting: Once anchored, Xiaomi's servers will start counting down (typically 168 hours for global versions).
3. Unlock via Mi Unlock Tool. Download the utility from the official website, log in to your Mi Account and connect your phone in fastboot mode (Off → Hold Power + Vol-).

⚠️ If the Mi Unlock Tool gives you a Couldn't unlock error, check it out: 🔌 Is the phone connected to the front? USB-port (rears often do not provide a stable connection). 🔄 If the antivirus and firewall are disabled, they can block the utility. 📱 Does the region of the Mi Account match the region of the firmware (for example, an account from Russia will not unlock a phone from the Chinese one) ROM).

Once successfully unlocked, the bootloader will remain unlocked even after resetting, but when the official firmware is installed via the Mi Flash Tool, it can lock again — that’s normal.

Installation of official firmware through Mi Flash Tool

This method is suitable for recovering the phone after a crash, upgrading to the latest version of MIUI or returning to the factory state. Importantly, the Mi Flash Tool only works on Windows (7/10/11). MacOS or Linux will have to use alternative methods (for example, through fastboot manually).

Step-by-step:

1. Download the firmware for lime (Redmi 9T) from the Xiaomi Firmware Updater. Choose the version of Fastboot (file with the extension.tgz).
2. Unpack the archive in a folder without Cyrillic characters (for example, C:\MIUI\lime_global_images_...).
3. Launch the Mi Flash Tool on behalf of the administrator. Press Select and point the path to the firmware folder.
4. Connect your phone to fastboot: Turn off the device. Press Power + Vol- until the Fastboot logo appears. Connect the cable to your PC.

Select firmware mode

• Clean all – complete cleaning (recommended in case of failures).
• Save user data – saving data (risk of error).
• Clean all and lock – Cleaning + locking the boot loader.
• Press Flash and wait until it is completed (5-10 minutes).

Download Fastboot firmware for lime|Unpack the archive to the root of the disk|Disable the antivirus|Connect the phone to the front USB-port|Run the Mi Flash Tool on behalf of the administrator

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If the process is stuck on Waiting for device, check:

• 🔌 Are the drivers installed correctly? ADB (Download from Android Developers).
• 🔄 Reboot your phone in fastboot again (Power) + Volume for 10 seconds).
• 🖥️ Try another one. USB-port.

⚠️ Warning: If the Mi Flash Tool is an anti-rollback error, you're trying to install firmware older than the current one. This is Xiaomi's protection against rollback to vulnerable versions. Solution: download a newer firmware or use a fastboot with a flag. --skip-secondary (power-user).

Install custom firmware (LineageOS, Pixel Experience)

Custom firmware gives Redmi 9T a second life: remove ads from MIUI, update Android to the latest version and improve performance, but installing them requires an unlocked bootloader and TWRP Recovery, an alternative recovery menu.

Steps to install (example Pixel Experience):

1. Download the firmware and TWRP: Firmware: Pixel Experience for lime (choose the lime version with suffix) -12 Android 12). TWRP: Official website (file) twrp-3.7.0_9-0-lime.img).

Install TWRP via fastboot

fastboot flash recovery twrp-3.7.0_9-0-lime.img


fastboot reboot recovery

The phone should boot up in the TWRP menu (if not, repeat the command).

Make a backup.

Backup

Boot

System

Data

Clear the sections.

Wipe → Advanced Wipe

Dalvik, Cache, System, Data

Install the firmware

Install

Install Gapps

OpenGapps

arm64 → 12 → pico

Reboot.

Reboot → System

The first download can take up to 15 minutes, and if the phone has been stuck on the logo for more than 20 minutes, it means there's been an error.

• 🔄 Come back in TWRP (Power + Vol+ loading).
• 📱 Repeat cleaning and installing the firmware.
• 🔧 Check the compatibility of the firmware version with your model (lime for Redmi) 9T).

💡

If your mobile network is not working after installing custom firmware, check your APN settings. Go to Settings → Mobile Network → Access Points (APN) and add your operator’s settings manually. Often the problem is solved by installing the correct APN for 4G/LTE.

Solving common errors in firmware

Even with strict adherence to instructions, failures can occur, and here are the most common mistakes and solutions:

If your phone is stuck in a bootloop (cyclic reboot), try:

1. Press the Power + Vol+ for 20 seconds to force shutdown.
2. Download to fastboot (Power + Vol-) and flash the official firmware through the Mi Flash Tool.
3. If it doesn't help, use it. EDL-Mode (requires an authorized Xiaomi account).

💡

If the sensors (gyroscope, compass) have stopped working after firmware, it is likely an incompatible core. Solution: run the firmware with the right vendor or install a patch for sensors (look for the 4PDA forum in the Redmi 9T theme).

How to return the official MIUI after custom firmware

If the custom ROM experiment didn't meet expectations, you can go back to the standard MIUI.

1. Download the official firmware in Fastboot format (not Recovery!).
2. Unpack the archive and find the file. flash_all.bat (for Windows or flash_all.sh (for Linux/Mac).
3. Connect your phone to fastboot (Power + Vol-)
4. Launch it. flash_all.bat This will automatically stitch all the sections, including boot and recovery.

Once rebooted, the phone will be like new, with all the factory settings. If you want to save data, back up your TWRP (if installed) before you run the firmware, or manually copy the files to your PC.

⚠️ Note: When returning to MIUI If you have a custom firmware, you can use anti-rollback protection, and if your phone is making an error and it doesn't turn on, you can run the newest version available. MIUI for your region.

FAQ: Answers to Frequent Questions