How to change the firmware on Xiaomi Redmi Note 9: official and alternative ways

Xiaomi Redmi Note 9 remains one of the most popular smartphones in the budget segment even years after its release. However, over time, standard MIUI firmware can start to slow down, and updates from the manufacturer stop coming out, in such cases, users think about manually replacing the firmware - whether it is a transition to the latest version of MIUI, installing custom software (for example, LineageOS or Pixel Experience), or even downgrade to a more stable build.

The Redmi Note 9 firmware process (codenamed merlin) has its own nuances, from the mandatory unlocking of the bootloader to the risk of “bricking” the device when errors occur. In this guide, we will analyze all the current methods, from official updates through Updater to install custom firmware through TWRP or Fastboot. Particular attention will be paid to the pitfalls of a particular model, such as problems with unlocking the bootloader on new versions of MIUI or incompatibility of some custom cores.

Important: If your goal is to simply upgrade to the latest version, check the availability first. OTA-Updates in the menu Settings → The phone. → System Update: Manual intervention is only required if the automatic update is not available or if you want to install alternative software.

1. Firmware Preparation: What to Do Before Starting

Before you start replacing your firmware, you need to follow a few critical steps, and neglecting them can lead to data loss, locking the device, or even a complete failure.

First, back up all the data. The firmware is basically reinstalling the operating system, and even if you choose the no-reset method, the risk of losing information remains. Use Mi Cloud, Google Drive, or local copying to your PC via MTP or ADB.

• 📱 Keep in touch (export to) VCF or synchronize with Google)
• 📷 Copy photos and videos (folders) DCIM, Pictures, Downloads)
• 🔑 Export passwords (from your browser or password manager)
• 📊 Save it. SMS and call logs (applications like SMS Backup & Restore)

Second, check the model and firmware version. Go to Settings → About the phone and write down:

• 📋 Model of the device (must be Redmi Note 9, codename merlin)
• 🔢 Version. MIUI (for example, MIUI 14.0.2 Global)
• 🤖 Android version (such as Android 12)
• 🔒 bootloader status (unlocked/locked – checked by the fastboot oem device-info command)

⚠️ Note: If your device was purchased in China (suffix version) CN in the model name), firmware of the global version MIUI This may cause problems with the module. NFC or LTE-In this case, it is recommended to use firmware marked EEA (Europe) or Global.

Finally, prepare the necessary tools:

2 Unlocking the bootloader: a mandatory step for any firmware

The bootloader is locked by default on all Xiaomi devices, a security measure that prevents unauthorized firmware changes, but any alternative firmware (even the official Fastboot) must be unlocked to install it.

The unlocking process includes several stages:

1. Linking your Mi Account to your device (required!).
2. Submit an application for unlocking via Mi Unlock Tool.
3. The waiting period for approval (can take up to 720 hours, i.e. 30 days!)
4. Direct unlocking via PC.

Detailed instructions:

1. Activate USB debugging: Go to Settings → About Phone. Click 7 times on MIUI to activate Developer Mode. Go back to Settings → Additional → Developer. Enable USB debugging and OEM unlock.

Link the Mi Account

• In the same menu for developers, find the status of Mi Unlock.
• Click Add Account and Device.
• Sign in with the same account you use in the Mi Unlock Tool.
• Install Mi Unlock Tool on PC and unlock: 1. Connect your phone to your PC in Fastboot mode (turn off the device, then press Power + Volume down). 2. Launch Mi Unlock Tool on behalf of the administrator. 3. Sign in to the same Mi. 4 account. Follow the program instructions. If you receive a waiting message, wait for the specified time (usually 168 or 720 hours).

⚠️ Warning: If you select Clean all and lock mode, the bootloader will lock again and the next firmware will require re-unlocking. Use this mode only if you are sure you will not change the firmware again!

Installation of custom firmware through TWRP

To install LineageOS, Pixel Experience or other custom firmware, you will need custom recovery – TWRP.

Instructions:

1. Install. TWRP: 1. Download the latest version TWRP for merlin from the official website. 2. Transfer the phone to Fastboot mode. 3. The command is fastboot flash recovery. twrp-3.7.0_9-0-merlin.img 4. Immediately after that, do: fastboot boot. twrp-3.7.0_9-0-merlin.img (This will load the device into TWRP, Not letting the stock firmware overwrite recovery).
2. Backup (optional but recommended): In TWRP, select Backup. Tap the Boot, System, Data, Vendor sections. Tap Swipe to Backup.

Install the firmware

• Download.zip firmware files and (if necessary) GApps placed on the phone or flash drive.
• V TWRP Choose Install → specify the firmware file → Swipe to Confirm Flash.
• After installing the firmware, repeat the step for GApps (if required).
• Run Wipe → Format Data (required for the first custom firmware installation!).
• Reset the device.

4. Solving problems after firmware

Even if you follow the instructions strictly, you can have problems, and let's look at the most common ones and how to fix them.

The device is not turned on (bootloop or brick)

If after firmware, the phone freezes on the logo or does not respond to buttons, try the following steps:

• 🔄 Hard reset: clamping down on the power supply + Loudness up on 10-15 seconds.
• 🛠️ Fastboot Flash: Connect the device to your PC in Fastboot mode. Follow the command: fastboot flash boot boot.img fastboot flash system system.img

Recovery through EDL

• You will need an authorized Xiaomi account and an EDL cable.
• Use tools like Mi Flash Pro or QFil.

4.2. touchscreen or sensors are not working

This problem often occurs when installing incompatible firmware or corrupting vendor files.

• 📱 Next Post:Fastboot Flash Vendor vendor.img
• 🔄 Get back to the stock. MIUI via Mi Flash Tool.
• 🔍 Check firmware compatibility with your version of the device (for example, firmware for Redmi Note 9 Pro will not work!).

4.3. No mobile network or Wi-Fi

Communication problems are usually related to:

• 📡 Wrong settings. APN (Check them manually with the operator).
• 📶 Lack of proprietary libraries (install firmware marked with a note) fw_vendor).
• 🔄 Incompatibility of the modem version (try flashing) modem.img stock-stack).