Xiaomi Redmi Note 9 remains one of the most popular budget smartphones even years after its release. However, over time, factory firmware may start to slow down, and updates through OTAs stop coming, in such cases, flashing the device becomes relevant — whether it is switching to a fresh version of MIUI, installing custom firmware like LineageOS or restoring functionality after a failure.
In this guide, we will look at all the current ways to run the Redmi Note 9 firmware (codenamed merlin), including official methods through the Mi Flash Tool and Recovery, as well as installing informal builds. We will focus on unlocking the bootloader, without which most operations are impossible, and the typical errors that users encounter. If you have never flashed a Xiaomi smartphone before, start with the introductory section, which explains the key concepts and risks.
Preparation for firmware: what you need to know before starting
Smartphone firmware isn’t just about pressing a few buttons. Wrong actions can turn the Redmi Note 9 into a brick, so it’s important to understand the basic principles:
- 🔓 Bootloader – by default locked on all Xiaomi devices. without it unlocking it is impossible to install custom software or even official firmware through Fastboot.
- 📱 Firmware versions: for Redmi Note 9 there are Global (international), China (Chinese), EEA (Europe and custom builds, you need to install the one that fits your model (M2003J15SC — global, M2003J15SS — Indian).
- 🔄 Firmware types: Recovery ROM — It's installed through stock recovery, it saves data. ROM — requires an unlocked bootloader, a complete partition rewriting. ROM — Unofficial firmware (e.g. Pixel Experience) requires custom recovery (TWRP).
Before you start, check:
- ⚡ Battery charge of at least 60% (when discharged during firmware, the device may turn off).
- 💾 Backup data (Fastboot firmware erases everything, including photos and contacts).
- 🖥️ The PC has installed Xiaomi drivers and ADB/Fastboot (You can download from the official website).
⚠️ Note: Fastboot firmware using the Mi Flash Tool automatically formats the userdata partition. If you don't backup, all personal files will be lost without recovery.
Unlock the bootloader on Redmi Note 9
Without unlocking the bootloader, you can’t flash Redmi Note 9 through Fastboot or install custom recovery.The process takes 7 days (from the moment you link your Mi Account to your device) and requires confirmation via SMS.
Step-by-step:
- Activate Developer Mode: Go to Settings → About Phone → MIUI version and tap 7 times on this item.
- Return to Settings → Additional → For developers and enable: Debugging over USB Unlock OEM (may be called Factory Unlock)
Mi Unlock
Mi
Fastboot
Loudness down + Nutrition
Unlock
⚠️ Warning: Once the bootloader is unlocked, the smartphone will reset to factory settings, all data, including apps and settings, will be deleted, and some features (e.g. Mi Pay or Widevine) will also be deleted. L1 viewable HD-Netflix videos may stop working.
☑️ Preparation for unlocking the loader
Firmware via Mi Flash Tool (official method)
Mi Flash Tool is Xiaomi’s official firmware utility for Fastboot devices, suitable for installing stock firmware (for example, when recovering from a crash) or upgrading to a new version of MIUI.
Download the current version of the Mi Flash Tool from the official website and firmware for your model (for example, merlin_global_images_V12.5.3.0.RJOMIXM_20220321.0000.00_11.0_global). Pay attention to the region’s compliance (Global, China, EEA).
Instructions:
- Unpack the archive with firmware in a folder without Cyrillic characters (for example, C:\miui_rom).
- Turn off the phone and put it in Fastboot mode (clamp Volume down + Power).
- Connect the device to your PC and start the Mi Flash Tool.
- In the utility, click Select and specify the path to the folder with the firmware.
- Select firmware mode: Clean all - complete cleaning (recommended in case of failures); Clean all and lock - cleaning + lock bootloader (only for official firmware); Save user data - data storage (not always stable).
Flash
| Firmware mode | Are the data stored? | Is the loader locked? | When to use |
|---|---|---|---|
| Clean all | ❌ No. | ❌ No. | If you have a critical failure or switch to another version of MIUI |
| Clean all and lock | ❌ No. | ✅ Yes. | To return to stock firmware with loader lock |
| Save user data | ✅ Yes. | ❌ No. | Update without data loss (error risk) |
If the Mi Flash Tool gives you an error "Couldn't find fastboot devices", check the driver installation and try connecting the phone to another device. USB-port (preferably) USB 2.0).
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If the firmware is stuck in the “waiting for device” stage, try restarting your phone to Fastboot again or using another one. USB-cable (preferably original).
Firmware through Recovery (without data loss)
Recovery is a method that can be used to install official MIUI updates without unlocking the bootloader. It saves user data, but only works with firmware in.zip format for Recovery ROM.
Download the necessary firmware from the official website (for example, miui_MERLINGlobal_V12.5.6.0.RJOMIXM_5d8a3f3a7d_11.0.zip) and transfer it to the root folder of the phone’s internal memory (not to the folder!).
Instructions:
- Go to Settings → About the phone → System update.
- Slap the icon. ⋮ (three dots) in the upper right corner and select Select firmware file.
- Specify the downloaded.zip file and confirm the installation.
- After restarting, the phone will automatically update (usually takes 10-15 minutes).
If the menu update is not available (for example, due to a system failure), use stock Recovery:
- Turn off the phone.
- Press Volume Up + Power to enter Recovery Mode.
- Choose a language (usually English or Chinese).
- Go to Install update.zip to System and specify the path to the firmware file.
- Confirm the installation and wait for completion.
⚠️ Warning: If your phone is stuck on the Redmi logo for longer than 15 minutes after you have been firmwareed through Recovery, reset it via Wipe Data in the same Recovery menu.
Installation of custom firmware (TWRP + Custom ROM)
Custom firmware such as LineageOS, Pixel Experience or ArrowOS allows you to get a pure Android without a MIUI shell, as well as more recent versions of the OS. However, they will require:
- 🔓 Unlocked loader.
- 🛠️ Established custom recovery (TWRP).
- 📄.zip firmware compatible with merlin.
Download the current version TWRP For the Redmi Note 9 from the official website (for example, twrp-3.7.0_9-0-merlin.img). Also prepare:
- Firmware (e.g. firmware, PixelExperience_plus_merlin-13.0-20230512-1200.zip).
- Magisk.zip file (if root is required)
- File. disable_force_encrypt.zip (to disable forced encryption).
Installation instructions:
- Transfer the phone to Fastboot mode and connect to the PC.
- Install. TWRP The command is fastboot flash recovery. twrp-3.7.0_9-0-merlin.img
- Immediately after installation, go to TWRP, holding Volume up + Power (otherwise, the stock firmware will overwrite recovery).
- In TWRP, run Wipe → Format Data (enter yes for confirmation).
- Return to the main menu and select Install, then specify the path to the custom firmware file.
- After installing the firmware, repeat the step to Magisk.zip (if root is needed, and disable_force_encrypt.zip.
- Reboot the phone (Reboot → System) The first launch can take up to 10 minutes.
What if TWRP doesn’t see internal memory?
Typical Firmware Errors and Their Solutions
Even with strict adherence to instructions, errors can occur, and here are the most common ones and ways to fix them:
| Mistake. | Reason. | Decision |
|---|---|---|
| Couldn't find fastboot devices | PC doesn't see the phone in Fastboot mode | Check it out. USB-Install Xiaomi drivers manually through Device Manager. Try another one. USB-port USB 2.0). |
| This package is for "merlin" devices; this is a "" | The firmware is not suitable for your model. | Download the firmware specifically for merlin (Redmi Note 9). Check the model code in Settings → About the phone. |
| Hanging on Redmi logo after firmware | Incompatible firmware or installation error | Log in to Recovery and run Wipe Data. Fastboot your phone with Clean all option. |
| Anti-rollback check fail | Trying to install an older version of MIUI | Use firmware with a version not lower than the current one. Check the version in Settings → About Phone → MIUI version. |
If the IMEI disappeared after the firmware or the mobile network did not work, the modem section was most likely damaged.
- Download the stock firmware for your model.
- Unpack it and find the NON-HLOS.bin file in the images folder.
- Fastboot: fastboot flash modem NON-HLOS.bin
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If after firmware the phone does not turn on at all (black screen, no reaction to buttons), try to pinch Volume up + Volume down + Power for 20 seconds - this will force the device to restart in emergency mode.
How to return stock firmware after custom
If custom firmware is unstable or you want to return the original MIUI, follow the following steps:
- Download Fastboot ROM for your model from the official website.
- Unpack the archive and launch the Mi Flash Tool.
- Connect your phone in Fastboot mode.
- In the utility, select Clean all and lock mode (this will block the bootloader and return stock recovery).
- Press Flash and wait until it is completed.
After the firmware:
- The phone will automatically reset to factory settings.
- The bootloader will be locked (unlocking will have to be done again if necessary).
- Features like Mi Pay and Widevine L1 will be restored.
⚠️ Note: If you have installed Magisk or modified system files, be sure to remove root and return all changes before returning to stock firmware. Otherwise, there may be firmware errors through the Mi Flash Tool.