Reinstall Android on Xiaomi Redmi 9: official and custom firmware

Introduction: Why Reinstall Android on Redmi 9

Smartphone Xiaomi Redmi 9 (codenamed lancelot) even after years remains popular due to balanced characteristics: the processor MediaTek Helio G80, 4 GB of RAM and battery 5020 mAh. However, over time, owners face typical problems: the system begins to “brake”, there are errors when updating through OTA, and the battery discharges faster than before. 80% of these problems are solved by a clean reinstallation of Android – a procedure that returns the smartphone factory performance.

Redmi 9 can be reflashed in three ways: 1) through built-in Recovery (the safest method for beginners), 2) with Fastboot (requires unlocking the bootloader), 3 by installing custom firmware such as LineageOS or Pixel Experience (for experienced users).

Each option has its own nuances: for example, the official firmware through the Mi Flash Tool will reset all data, and custom can deprive you of warranty. In this article, we will analyze all methods taking into account the current versions of MIUI 14 and Android 12, which were updated Redmi 9 in 2026.

⚠️ Critical Warning: If Your Smartphone Is Bought in China (Suffix Version) CN In the model), reflashing to the global version MIUI can block the modules NFC or 5G (If you have any, check the model in Settings → The phone. → Model before the beginning!

Preparation for reinstallation: backup and unlock

The first step is to save important data. Fastboot or Recovery flashing completely clears the internal memory (partition /data).

• 📱 Contact and SMS: Sync with your Google Account (Settings) → Accounts. → Google → Synchronization).
• 📷 Photo/video: copy to PC via MTP Or upload it to Google Photos.
• 🔑 Apps: export the list through Mi Mover or ADB-Team: adb backup -apk -obb -shared -all -f backup.ab
• 📄 Documents: Move to MicroSD or to the cloud (Mi Cloud, Yandex Drive).

The second stage is unlocking the bootloader (only for the Fastboot method). Xiaomi blocks the bootloader on all devices, so without this procedure, you will not be able to flash the smartphone with official firmware.

1. Link your Mi Account to your phone (Settings → Xiaomi Account).
2. Activate USB Debugging in Settings → About Phone → MIUI Version (click 7 times) → Additional → For Developers.
3. Connect the phone to the PC, confirm the debugging permission.
4. Download Mi Unlock Tool, log in to your account and follow the instructions (unlock time is up to 72 hours!).

⚠️ Warning: Once the bootloader is unlocked, the smartphone will perform a hard reset.All data will be deleted even if you haven't started firmware! Also note that Xiaomi can block unlocking if the phone was purchased less than 30 days ago.

Method 1: Reinstallation via Recovery (without PC)

This is the simplest method that doesn't require unlocking the bootloader, it's good for restoring the system if the smartphone is switching on but is not stable, and it's important that the firmware version is the same as the current one (for example, if you have MIUI 14, download it).

Instructions:

1. Download the official firmware for Redmi 9 (lancelot code) from Xiaomi Firmware. Choose a file with the.zip extension and the Recovery tag.
2. Rename the file to update.zip and move it to the root folder of the phone’s internal memory (not to folders!).
3. Turn off the phone. Press Volume up + Power to enter Recovery.
4. Select the language, then go to Install update.zip to System.
5. Confirm installation. Once completed, select Reboot to System.

SHOWS official ZIP for recovery|File renamed to update.zip|The file is at the root of the memory.|Battery charge > 50%|Data backup executed-->

⚠️ Note: If the phone has been stuck on the Redmi logo for more than 10 minutes after the reboot, then the firmware does not fit your version).

fastboot flash recovery recovery.img

(file recovery.img can be extracted ZIP-firmware).-->

Method 2: Fastboot Firmware (from PC)

This method is suitable for “brick” phones (do not include, hang on the logo) or when you need to downgrade the version of MIUI.

• 🖥️ Windows PC 10/11 (For the Mi Flash Tool).
• 🔌 Cable USB Type-C (original, undamaged!).
• 📦 Firmware in.tgz or.zip format for Fastboot.
• 🛠️ The Mi Flash Tool.

Step-by-step:

1. Unpack the firmware in a folder without Cyrillic characters (for example, C:\MIUI\lancelot_fastboot).
2. Turn off the phone. Press Volume down + Power to enter the Fastboot (there will be a picture of a hare in a hat-eared).
3. Connect your phone to your PC. Launch the Mi Flash Tool, press Select, and point the path to the firmware folder.
4. At the bottom, select Clean All (Full Cleaning) or Clean All and Lock (Cleaning + Lock bootloader).
5. Press Flash. It takes 5-10 minutes.

⚠️ If the Mi Flash Tool is a bug, you can’t find fastboot:

• Are Xiaomi drivers installed (download through the official website).
• Are you using it? USB-Hub (connect directly to the PC port).
• Does the antivirus block access to the utility (add Mi Flash Tool to exceptions).

💡

Fastboot is the only way to bring back a phone that doesn't turn on or is stuck on the logo, but it requires an unlocked bootloader and erases all data.

Method 3: Install custom firmware (LineageOS, Pixel Experience)

Custom firmware gives Redmi 9 new features: clean Android without ads, security updates longer than Xiaomi, and additional features (like Always-on Display).

• 🚫 Loss of warranty (if you don’t return stock firmware).
• 📵 Possible camera or Wi-Fi issues (depending on build).
• 🔋 Increased battery consumption (due to unoptimized core).

Instructions for LineageOS 20 (based on Android 13):

1. Unlock the bootloader (see Section 2).
2. Download: LineageOS firmware (select the latest build). Open GApps (pico or nano variant). TWRP Recovery for Redmi 9.

TWRP

Fastboot

fastboot flash recovery twrp.img


fastboot reboot recovery

TWRP

Wipe → Advanced Wipe

Dalvik, Cache, System, Data

LineageOS

GApps

Solving errors when reinstalling Android

Even with accurate follow-up, there may be failures, and let's look at the typical errors and their solutions:

Important for owners of Redmi 9 with a MediaTek Helio G80 processor: if after firmware the phone is no longer detected by the PC in Fastboot mode, use the SP Flash Tool utility instead of the Mi Flash Tool. Download it from the MediaTek website and swipe the scatter file from the firmware archive.

If none of the methods worked, check:

• 🔋 Battery charge (should be) > 30%, otherwise the firmware will be interrupted).
• 🔌 Cable and port USB (Try another cable or port on your PC).
• 🛠️ Mi Flash Tool version (new firmware requires version not lower than 2023.4.28.0).

How to return the guarantee after flashing

If you have installed custom firmware or unlocked the bootloader, Xiaomi may refuse warranty repairs. To return everything "as it was", do:

1. Download the official firmware for your model from the Xiaomi website (Fastboot format).
2. Swipe it through the Mi Flash Tool in Clean All and Lock mode.
3. After the reboot, reset to factory settings (Settings → Additional → Restore and Reset).
4. Check the status of the bootloader command: fastboot oem device-info Device unlocked: false means that the bootloader is locked.

⚠️ Note: if you have been using custom Recovery (e.g, TWRP), You have to go back to the standard one, too. recovery.img firmware:

fastboot flash recovery recovery.img


fastboot reboot recovery

FAQ: Frequent questions about reinstalling Android on Redmi 9