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

Xiaomi Redmi 9T is a popular smartphone with a balance of price and performance, but even it requires a firmware update over time. Whether it is an official update to MIUI for bug fixes or custom firmware for advanced features, the firmware process can seem complicated. In this article, we will analyze all the ways to implement Redmi 9T firmware (codenamed lime), from preparation to solving possible errors.

It's important to understand that firmware is not only a way to get new features, but it also risks turning a phone into a brick if you do everything at random. We will describe each step in detail, including unlocking the bootloader, selecting the firmware and restoring the system after unsuccessful manipulations, focusing on official methods (via Fastboot and Recovery) and custom solutions (TWRP, LineageOS).

If you're a beginner, start with the official instructions. Experienced users will find the nuances of working with the Internet. EDL-Don't miss the typical error section, it will save you hours of searching for solutions.

1. Firmware Preparation: What to Do Before Starting

Redmi 9T firmware requires advance actions, without which the process can end in error or loss of data. Start with backup: even an official update sometimes resets settings.

List of mandatory training:

• 📱 Save data: contacts, photos, messages (use Mi Cloud or local copying on PC).
• 🔋 Battery charge: at least 60%, and when discharged during firmware, the phone may turn off, causing a failure.
• 🖥️ Install drivers: Xiaomi will need to be installed ADB/Fastboot Qualcomm Drivers (if you plan to work in the same area) EDL).
• 🔓 Unlock the bootloader: without this custom firmware can not be installed (more about this in the next section).

To work with firmware download:

• 📁 Official firmware from the site MIUI Download (select the version for lime).
• 🛠️ Tools: Mi Flash Tool (for Fastboot), Platform Tools (ADB/Fastboot), TWRP (custom-fix).

⚠️ Note: If you flash a phone with a locked bootloader through Fastboot, the system automatically erases all data (including internal memory). SD-backup.

2 Unlock the bootloader on the Redmi 9T

The bootloader on Xiaomi Redmi 9T is locked by default. To install custom firmware or modified cores, it must be unlocked. The process takes up to 7 days due to Xiaomi's policy (mandatory confirmation waiting).

Step-by-step:

1. Link your Mi Account: go to Settings → Mi Account → Link your account to your device.
2. Enable USB debugging: in Settings → About Phone → MIUI version tap 7 times, then in Settings → Additional → For developers, activate USB debugging and OEM unlock.
3. Download Mi Unlock Tool: official software from Xiaomi website (Windows only).
4. Connect your phone to Fastboot: Turn off the device, press Volume Down + Power, then connect to the PC.
5. Start unlocking: in Mi Unlock Tool, log in to your account and follow the instructions. The system will offer to wait 168 hours (7 days).

Once unlocked, the bootloader will remain open, but every time you run through Fastboot, the data will be reset.This is a security measure from Xiaomi.

⚠️ Note: If you bought the phone with your hands, make sure the previous owner untie your Mi Account. Otherwise, unlocking will not be possible without his data.

3.Official firmware via Fastboot

The method is suitable for system recovery after a failure or upgrade to the latest version of MIUI. Mi Flash Tool is the official software from Xiaomi.

Instructions:

1. Download the firmware: select the version for lime (for example, lime_global_images_V12.0.1.0.QJQMIXM_20210112.0000.00_10.0_global) and unpack the archive.
2. Install Mi Flash Tool: Launch the installation file and follow the wizard.
3. Transfer your phone to Fastboot: Turn off the device, press Volume down + Power.
4. Connect to your PC: wait for the device definition (Android Bootloader Interface should appear in Device Manager).
5. Start the firmware: In the Mi Flash Tool, specify the path to the unpacked firmware, select Clean All mode (full clean) and press Flash.

It takes 5 to 10 minutes, and when it's done, it automatically reboots, and the first time it's turned on can take up to 15 minutes, which is normal.

⚠️ Note: If after firmware the phone is stuck on the Redmi logo, try re-swipe in Clean All mode. If this does not help - you need firmware through the EDL (see section 5).

4. Install custom firmware (TWRP + LineageOS)

Custom firmware like LineageOS or Pixel Experience gives you more freedom: no ads in MIUI, up-to-date Android updates and advanced settings, but installing them requires an unlocked bootloader and a TWRP installed.

Steps to install LineageOS:

1. Download TWRP: The official version for lime from the TWRP website.
2. Install. TWRP Fastboot: Fastboot Flash Recovery twrp-3.7.0_9-0-lime.img fastboot boot twrp-3.7.0_9-0-lime.img
3. Download firmware: for example, LineageOS 20 (Android 13) from the LineageOS website.
4. Transfer files to your phone: connect your device to your PC in MTP mode (via TWRP) and copy firmware and GApps (if you need Google services).
5. Sweat through TWRP: in recovery, select Wipe → Format Data (required!), then Install and specify the firmware file.

After installation, the first boot can take 10-20 minutes. If the system does not start, check the firmware compatibility with your model (lime for Redmi 9T).

Advantages of custom firmware:

• 🚀 Clean Android: without unnecessary apps and advertising from Xiaomi.
• 🔄 Long updates: LineageOS supports devices longer than the official MIUI.
• ⚙️ Flexible settings: advanced options for performance and design management.

💡

If your mobile network is not working after installing custom firmware, check your APN settings or run a separate modem file for your region.

5. Firmware through EDL: Restore the "brick"

EDL (Emergency Download Mode) is the last chance to bring the Redmi 9T back to life if it doesn't turn on or hangs on the logo. This method requires a special cable (EDL cable) or short circuit test points on the board.

Important: Firmware through EDL erases IMEI and serial number if you use informal tools.

Instructions:

1. Transfer the phone to EDL: Method 1: Use EDL cable (the jumper between GND and EDL contacts in the USB connector). Method 2: Shortly close the test points on the motherboard (disassembly required).

Install the drivers:

Qualcomm HS-USB QDLoader 9008

XDA

4PDA

Mi Flash Tool

.mbn

Flash

If the phone does not detect after the firmware SIM-maps, restore them. IMEI With tools like Maui META or SN Write Tool (requires backup copies).

⚠️ Attention: Firmware through EDL Without a backup of nvdata, it can cause loss IMEI. If you are not sure about your actions, contact the service center.

Typical errors and their solutions

Even when you follow instructions, you can get errors, and we've collected some of the most common problems and ways to solve them.

If you encounter an error not described here, check the firmware logs (in Mi Flash Tool or TWRP) and search for a solution on the XDA Developers or 4PDA forums (indicate the exact name of the error).

💡

90% of firmware errors are due to an unblocked bootloader, the wrong firmware version, or the absence of drivers. Always check these points first.

7.How to get back the official MIUI after custom firmware

If custom firmware was unstable or you want to return the warranty, you can restore the official MIUI.The process is similar to the original firmware through Fastboot, but there are nuances.

Step-by-step:

1. Download the official firmware: select the version for your region (e.g, lime_eea_global_images... Europe).
2. Unlock the bootloader: if it was blocked after installing custom firmware, repeat the unlocking procedure.
3. Fastboot: Use Clean All and Lock mode in the Mi Flash Tool to return factory settings and lock the bootloader.
4. Check the work: after firmware, reset through Settings → Restore and reset.

Try a different USB port or reinstall the drivers manually through Device Manager.