Install firmware on Xiaomi Redmi Note 9: full instruction with unlocking the bootloader

The Xiaomi Redmi Note 9 (codenamed merlin) remains a popular smartphone even years after its release, but its owners often face the need to reflash the device. The reasons range from wanting to update an outdated version of MIUI to having to restore the phone after a crash. In this article, we will discuss all the ways to install firmware — through Recovery, Fastboot and the official Mi Flash Tool — and also explain how to avoid errors that turn the smartphone into a “brick”.

It’s important to understand that the Redmi Note 9 firmware is different from the same procedure on new Xiaomi models (like the Redmi Note 12 or POCO X5). There are nuances here with unlocking the bootloader, choosing the right version of MIUI (global, Chinese, EEA) and even with drivers for PC. If you’ve never flashed a smartphone before, start with the section on preparation – this will save hours on bug fixes.

1. Firmware Preparation: What to Do Before Starting

The first step is to save all the important data. The firmware, especially through Fastboot, erases the device's internal memory. Use Mi Cloud, Google Photos, or physical copying to your PC. Note: TWRP backups (if installed) may not recover after you change the MIUI version.

Next, check the current firmware version and device model.

• 📱 Go to Settings. → The phone. → Version. MIUI.
• 🔍 Remember the assembly number (for example, V12.5.3.0.RJOMIXM).
• 🛠️ Make sure the Redmi Note 9 is the model (not the Note 9 Pro or Note). 9S), because the firmware is incompatible!

Also prepare:

• 💻 Windows computer 7/10/11 (For the Mi Flash Tool).
• 🔌 Original. USB-cable (cheap cables can interrupt data transmission).
• 🔋 Battery charge of at least 60% (when discharged during firmware, the device may turn off).
• 📁 Firmware that matches your model (more on this in the next section).

⚠️ Note: If you install custom firmware (like LineageOS or Pixel Experience), first unlock the bootloader through the official Xiaomi tool.

2. Selection of firmware: official MIUI or custom?

There are several types of firmware available for the Redmi Note 9:

For most users, the best choice is the official firmware in the format of Fastboot.

• 🔄 Recovery of the phone after a failure ("brick»).
• 📲 Updates to the new version MIUI (for example, 12 to 13).
• 🔓 Unlock additional features (e.g. Google Camera).

If you download firmware from third-party resources (not from the official Xiaomi site), check the hash files (MD5) through the MD5 Checker utility.

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Before downloading the firmware, disable the VPN and antivirus – they can block the download of large files from official Xiaomi servers.

3. Unlocking the bootloader: a must-do step for Fastboot and custom firmware

Xiaomi blocks the bootloader on all devices, including the Redmi Note 9, which means that without official unlocking, you will not be able to:

• 📦 Install firmware through Fastboot.
• 🔧 Install TWRP or custom-recovery.
• 🤖 Sweep custom firmware (for example, LineageOS).

The unlocking process takes up to 72 hours (sometimes longer) and requires:

1. Linking your Mi Account to your device (in Account settings → Mi Account).
2. Install the Mi Unlock Tool on PC (download here).
3. Transfer the phone to Fastboot mode (clamp Power + Volume down).
4. PC connections and SMS waits with unlock confirmation.

⚠️ Note: If you previously unlocked the bootloader on this device, but then flashed the official download MIUI via the Mi Flash Tool with clean all option, the bootloader could lock again. Check the status of the command fastboot oem device-info in the terminal.

Once you've successfully unlocked, you'll see a message called Unlocked successfully. Now you can start the firmware. If you haven't unlocked, try:

• 🔄 Repeat the process after 24 hours (Xiaomi servers may be overloaded).
• 📡 Use a different Mi Account (sometimes helps).
• 🖥️ Run Mi Unlock Tool on behalf of the administrator.

4. Install firmware via Fastboot (Mi Flash Tool)

This is the most reliable way to flash the Redmi Note 9, but it requires an unlocked bootloader and erases all data.

1. Download the firmware in Fastboot format (file with.tgz or.zip extension) and unpack it into a folder without Cyrillic characters (for example, C:\MIUI\merlin).
2. Install the drivers: 🖥️ Download Mi. USB Driver and install it. 🔌 Connect the phone in Fastboot mode (clamp Power). + Volume down when the phone is off). 🔍 In Device Manager, check that the phone is defined as Android Bootloader Interface.
3. Launch the Mi Flash Tool: 📁 Unpack the archive with the utility and run MiFlash.exe on behalf of the administrator. 🔗 Click Select and point the way to the folder with unpacked firmware. 📋 Select firmware mode at the bottom: clean all – complete cleaning (recommended when changing version) MIUI). Clean all and lock - cleaning + bootloader lock (only for official firmware!) save user data - data storage (not always stable).

Start the firmware

Flash

If the Mi Flash Tool is making an error, check:

• 🔌 Cable and port USB (Try the port USB 2.0 on the back of the PC).
• 📁 The path to firmware (should not be Cyrillic or gaps).
• 🔄 Mi Flash Tool (new firmware may require the latest version of the utility).

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Clean all and lock lock locks the bootloader back. Use it only for official Xiaomi firmware. For custom firmware, this mode will lead to a brick.

5. Install firmware via Recovery (without unlocking the bootloader)

If you don’t need to change the MIUI version drastically (for example, from 12 to 13), but only update the current one, you can use Recovery. This method does not require unlocking the bootloader and does not erase user data (but we recommend backup!).

Instructions:

1. 📁 Download the firmware in Recovery format (.zip file) from the Xiaomi Firmware Updater website.
2. 📱 Rename the file to update.zip and transfer it to the root of the phone’s internal memory (not to folders!).
3. 🔄 Go to Settings. → The phone. → Updating the system.
4. 🖱️ Click on the three dots in the upper right corner and select Select the firmware file.
5. 📄 Indicate. update.zip and confirm installation.

The phone will reboot in Recovery and start installing. It will take 5-15 minutes. Don't interrupt it! If after the reboot the phone hangs on the Redmi logo, reset via Recovery (Wipe Data).

⚠️ Attention: Recovery firmware is often delayed compared to Fastboot.If you need the latest version MIUI, Use the Mi Flash Tool.

If the installation through System Update does not work (for example, due to damaged Recovery), you can manually flash:

1. Turn off the phone.
2. Press Power + Volume Up to Enter Recovery.
3. Select Install update.zip to System (navigation – volume buttons, confirmation – power button).
4. Confirm the installation and wait for completion.

6. Solving common firmware errors

Even when you follow the instructions, you can get errors, and here are the most common ways to correct them:

If the Mi Flash Tool is 0x80070002 or 0x80004005, it is usually due to:

• 📁 On your way to the firmware (transfer the folder to disk C: and rename it to miui).
• 🔌 Problems with USB-port (try the port) USB 2.0).
• 🖥️ Antivirus (disable Windows Defender or add Mi Flash Tool to exceptions).

If the IMEI is missing after the firmware or the network is not working, restore it through the engineering menu:

1. Please dial the phone application ##4636##.
2. Go to Phone Information and check for IMEI status.
3. If IMEI is not available, use the SN Write Tool (requires authorization on Xiaomi servers).

7. firmware custom Recovery (TWRP) and custom firmware

If you want to install LineageOS, Pixel Experience or other custom firmware, you first need to flash TWRP Recovery, which is more risky than installing an official MIUI, but it provides more features.

Instructions:

1. Unlock the bootloader (as described in Section 3).
2. Download TWRP for Redmi Note 9 (merlin) from the official website: twrp.me.
3. Log in to TWRP and backup the persist partition (important to save IMEI!).

After installing custom firmware, you may need to flash:

• 🔒 Magisk (to obtain root rights).
• 📡 GApps (if the firmware is without Google services).
• 🔋 GCam-enabled kernel (for improved camera).

⚠️ Note: Castom firmware may not support Widevine L1 (no HD Netflix, Disney.+). To check the Widevine level, install the application DRM Info from Play Market.

8.Optimization after firmware: what to do first

After successful firmware (especially if you have installed a new version of MIUI or custom firmware) follow these steps to work steadily:

• 🔄 Reset the settings to factory settings (if you were flashing through Fastboot with the clean all option) and this will eliminate possible data conflicts.
• 🔒 Turn on the developer and turn off MIUI Optimization (in the developer settings) This will speed up the system.
• 📡 Update all apps through the Play Market (especially Google Play Services).
• 🔋 Calibrate the battery: Charge the phone to 100%. Turn off the charge and use until full discharge. Repeat the cycle 2-3 times.

Install Google Camera

Redmi Note 9

GCam 8.1

BSG

If after firmware appeared bugs (for example, quickly dies battery or lays the interface), try:

• 🔄 Return to the previous version MIUI (If you were running through Fastboot).
• 🔧 Disable animations in the developer settings (Window animation scale) → 0.5x).
• 📵 Reset network settings (Settings) → SIM-maps and mobile networks → Resetting network settings).

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After you have run through Fastboot, always check the sensors (gyroscope, compass, NFC) using the Play Market’s Sensor Test app. If the sensors don’t work, run the firmware again with the “clean all” option.

FAQ: Frequent questions about the Redmi Note 9 firmware