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

Xiaomi Redmi Note 9 remains one of the most popular budget smartphones even years after its release. However, over time, the regular MIUI firmware begins to slow down, and updates from the manufacturer stop coming out, in such cases, users resort to manual flashing — whether it is the official global version or custom build like LineageOS or Pixel Experience.

This guide will take a look at all the steps from the device preparation to the final setup after installation, and we will look at two main scenarios: updates via Fastboot (for official firmware) and TWRP (for custom ones), and pay special attention to common mistakes that plague beginners, such as locking the bootloader or “bricking” the device due to the wrong version of firmware.

Important: The procedure requires precision. 9 with a Mediatek Helio processor G85 (codename merlin) and G80 (merlin_in) The algorithm for unlocking a bootloader is different from Snapdragon devices. ADB Fastboot, we recommend you first learn the basic commands.

1. Device Preparation: What to Do Before Firmware

The first step is to back up your data, and even if you plan to install the official firmware without resetting your settings, you still have the risk of losing your data. Use Mi Cloud or third-party tools like Titanium Backup.

• 📱 Contacts and messages (export to.vcf and.xml)
• 📷 Photos and videos (transfer to PC or cloud)
• 🔑 Passwords from apps (use Bitwarden or analogues)
• 🎮 Save games (via Helium or manual backup folder) /Android/obb)

Next, check the current firmware version. Go to Settings. → The phone. → Version. MIUI. Write down the full title (for example, MIUI Global 12.5.3 Stable and device code (merlin or) merlin_in). This information will be needed to select the correct firmware file.

⚠️ Note: If your Redmi Note 9 is purchased in China (suffix version) CN), firmware of the global version without prior unlocking the bootloader will lead to permanent locking IMEI. In this case, you will need to contact the service center.

Also prepare:

• 🔌 Cable USB Type-C (original or certified)
• 💻 Windows computer 10/11 Linux (MacOS is not recommended due to driver issues)
• 🔋 Battery charge of at least 60%
• 🛠️ Used by Mi Flash Tool, ADB/Fastboot, TWRP (if you need custom firmware)

2. Unlocking the bootloader: step-by-step guide

The bootloader on Xiaomi Redmi Note 9 is locked by default.To install any firmware (except for the one on the phone). OTA-Updates, it needs to be unlocked, takes up to 72 hours due to Xiaomi's policy.

Steps to unlock:

1. Link your Mi Account to your device: Settings → Xiaomi Account → Sync.
2. Enable USB Debugging and OEM Unlock in Settings → About Phone → MIUI version (tap 7 times on version to activate the developer menu).
3. Download Mi Unlock Tool and log in to the program.
4. Connect your phone in Fastboot mode (clip Power + Volume down when the device is off).
5. If you receive a message about the need to wait, wait for an SMS from Xiaomi (usually 3-5 days).

⚠️ Warning: Once unlocked, the bootloader will reset all data on the device, including internal memory.Don't rely on backups created after unlocking - they may contain artifacts from the old system.

If the utility gives you a "Couldn't unlock" error, check:

• My account is tied to the phone for more than 7 days.
• The device has the latest version of MIUI installed (update via Settings → System Update).
• You use the original cable and USB 2.0 port (problems are more common with USB 3.0).

Linked to the Mi Account to the device|Debugging is on. USB|Downloaded Mi Unlock Tool|Phone's 60-charged%+|There's a backup of the data.-->

3. Installation of the official firmware through Fastboot

The official firmware for Redmi Note 9 is available in two formats:

• Recovery ROM – installed through stock recovery (without unlocking the bootloader, but with restrictions).
• Fastboot ROM – full system image, requires Mi Flash Tool and unlocked bootloader.

We recommend Fastboot as a more reliable method, download the firmware from the official Xiaomi website by selecting the merlin model (for the global version) or merlin_in (The file is in.tgz format, unpack it into a folder without Cyrillic characters.

Installation instructions:

1. Turn off the phone and press Power + Volume down to log into the Fastboot.
2. Connect the device to your PC and run the Mi Flash Tool (on behalf of the administrator).
3. In the program, click Select and specify the path to the unpacked folder with firmware.
4. Select Clean All (full reset) or Clean All and Lock (reset + lock bootloader).
5. Press Flash and wait until it's finished (10-15 minutes).

If the process is stuck in the “flash boot” stage, check:

• Correctness of the selected firmware (for merlin, a file from the merlin_in vice versa).
• The lack of Chinese characters on the way to the firmware folder.
• Mi Flash Tool (new firmware may require the latest beta version of the utility).

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If you've got your phone stuck on the MI logo after you've done it, press Power + Volume up for 15 seconds to force you to restart. If that doesn't work, repeat the procedure with Clean all mode.

4. Install custom firmware through TWRP

Custom firmware like LineageOS or Pixel Experience offers more features: pure Android without bloat, regular security updates and advanced settings, but they require an unlocked bootloader and TWRP Recovery to install.

Download it first.

• 📱 TWRP For the Redmi Note 9 (The version must be in accordance with the device code, merlin or merlin_in). Look for official builds on twrp.me.
• 🖥️ Firmware (e.g. LineageOS 20 for merlin from lineageos.org).
• 🔄 Open GApps (if you need Google services; choose the option) arm64 → 11.0 → pico for Android 11).

Installation of TWRP:

fastboot flash recovery twrp-3.7.0_9-0-merlin.img


fastboot reboot recovery

After you log in to TWRP, do:

1. Swipe to allow modifications (if requested).
2. Go to Wipe → Format Data, type in yes and confirm (this will delete everything, including internal memory!).
3. Return to the main menu and select Install, then specify the path to the firmware file (e.g. lineage-20.0-20231010-nightly-merlin-signed.zip).
4. After installing the firmware, repeat the step for GApps (if needed).
5. Reboot to the system (Reboot → System).

⚠️ Attention: On the Redmi Note 9 Android-based firmware 12+ You may need to disconnect AVB (Android Verified Boot, otherwise the device will not boot. TWRP Follow the command: fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img (file vbmeta.img usually comes with a firmware).

5. Typical errors and their solutions

Even if you follow the instructions accurately, users face problems.

If after installing custom firmware does not work:

• 📶 Mobile Network: Check the settings APN or patch it. IMS (for LineageOS).
• 🔊 Sound: Proprietary drivers may not be installed. Download vendor and firmware for your model.
• 🔋 Fast battery discharge: calibrate the battery (discharge to 0%, charge to 100% without interruptions).

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If the phone does not detect after the firmware SIM-The card is likely to be missing a modem. Install the stock firmware via Fastboot, then re-install the customization.

6. System optimization after firmware

After successful firmware installation, it is recommended to follow several steps for stable operation:

For the official MIUI:

• 🚀 Disable unnecessary system applications through Settings → Annexes → Application management (e.g. Mi Video, Mi Music).
• 🔄 Update all apps through Google Play.
• 🛡️ Enable Battery Optimization for Frequently Used Applications.

For custom firmware:

• 🔧 Install FrancoKernel or Kirisakura kernel to improve performance (optional).
• 🎨 Set up theme and animations through Settings → System system → Advanced settings.
• 📊 Check the temperature of the processor using AIDA64 — if it exceeds 50°C in simple, you may need to flash the thermal-engine.

For all types of firmware:

• 🔄 Perform a cache reset (Wipe) → Cache in TWRP or through the settings → Memory. → Cleanup).
• 📱 Install Magisk for root rights (if necessary). Download the latest version from GitHub and run through TWRP.

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To speed up MIUI, turn off the animation interface. To do this, activate Developer Mode and in Settings → Additional → For developers, set all animation values to 0.5x or Off.

7. How to roll back on a previous firmware version

If the new firmware is unstable, you can return the previous version. MIUI:

1. Download the desired version from the official website.
2. Unpack the.tgz archive and run through the Mi Flash Tool in Clean All mode.

For custom firmware:

1. Download the previous build (e.g. LineageOS 19 instead of 20).
2. In TWRP, run Wipe → System, then install the old firmware and GApps.
3. Reboot. If you have any errors, repeat the full formatting procedure.

⚠️ Note: Retreat to an earlier version MIUI This can lead to a bootloader lock if the new firmware has an anti-rollback update. Before the procedure, check the list of blocked versions for your model on the forums XDA Developers.

8.Where to look for current firmware and updates

The official firmware for the Redmi Note 9:

• 🌍 Global versions: miui.com (choose merlin).
• 🇮🇳 Indian versions: miui.com/in (merlin_in).
• 🇨🇳 Chinese versions: miui.com/cn (Requires manual installation of Google Services).

Castom firmware:

• 📱 LineageOS: download.lineageos.org
• 📱 Pixel Experience: download.pixelexperience.org
• 📱 ArrowOS: arrowos.net
• 📱 Havoc-OS: havoc-os.com

Before downloading, check:

• Date of assembly (up-to-date versions are released at least 1 time per month).
• Forum reviews (XDA, 4PDA) – some builds may have critical bugs.
• firmware requirements (e.g., Pixel Experience may require stock vendor firmware pre-firmware).

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For stable operation of custom firmware on Redmi Note 9, it is recommended to use firmware from the latest official MIUI. Download it separately and flash before installing the custom OS.

FAQ: Frequent questions about the Redmi Note firmware 9