Modern MIUI shells, which are installed by default on Xiaomi devices, are often criticized for the abundance of advertising, pre-installed software and background processes that consume battery power. Users who want to get the maximum performance and response speed of the interface often pay attention to projects with pure Android, known as AOSP (Android Open Source Project), switching to such a system on the Redmi 9 model allows you to significantly extend the life of the gadget, turning a budget device into a quick tool for everyday tasks.
The process of replacing the operating system requires careful and strict adherence to the sequence of actions, since interference with the software can lead to data loss or device failure. Unlike a standard update, installing custom firmware involves gaining advanced access rights and replacing the system partition. However, if done correctly, you will get a system devoid of unnecessary “garbage”, with current security patches and smooth animation.
Before you start taking action, you have to realize that this procedure voids the manufacturer's official warranty. You do all the manipulations at your own risk, so it's critical to back up all the important data, because the internal memory will be completely cleaned up in the process. Preparation takes up to 80% of the time of the entire operation, and rush is the main enemy of successful results.
Preparation for firmware and unlocking the loader
The first and most important step is unlocking the bootloader. Without this step, installing a modified backup or new firmware is technically impossible, since Xiaomi's security system blocks the launch of unverified code. You will need a Mi Account tied to the device and a Mi Unlock Tool installed on a Windows computer. The binding process can take from 7 to 168 hours, which is the company's standard security procedure.
After successful unlocking, you need to make sure that you have all the necessary drivers and tools on your PC. Lack of the right ADB and Fastboot drivers is the most common reason why your computer does not see your smartphone in bootloader mode. It is also worth checking the charge of the device, which should be at least 60-70%, to avoid suddenly turning off at a critical time of writing system files.
- 📱 Charge your smartphone to at least 70% for stable operation.
- 💻 Install the drivers. ADB and Fastboot on the computer.
- 🔓 Link your Mi Account in the developer settings.
- 📂 Make a full backup of the data to an external medium.
⚠️ Note: Once the bootloader is unlocked, Find the Device will be forced off and all data on the phone will be erased.
Installation of custom TWRP Recovery
The standard recovery menu does not allow installing third-party operating systems, so installing TWRP (Team Win Recovery Project) is a specialized environment that gives full access to the device's memory partitions. Redmi 9 (codenamed lancelot or merlin depending on the processor) requires downloading a strictly appropriate version of the.img image, since the firmware from another model will turn the device into a "brick".
The process of recavator firmware is done via Fastboot mode. Once you connect your smartphone to your PC, press the combination of volume reduction and power buttons. In the computer command line, type a command to check the connection and then a command to record the image. It is important to understand that after the first reboot, a regular loader can replace the TWRP back with stock Recovery, if you do not take special measures immediately after installation.
fastboot flash recovery twrp-3.x.x-x-lancelot.img
fastboot boot twrp-3.x.x-x-lancelot.imgTo save TWRP, you have to reset your settings and reboot your system immediately after you enter Recovery, or you have to flash a patch that blocks the Recovery, and if you ignore that, you have to repeat the Fastboot input every time, which is very inconvenient. The successful installation of the Custom Recovery is a halfway point, which means that halfway through.
☑️ Pre-firmware check TWRP
Choosing the Right Firmware for Clean Android
Choosing an operating system is not just a matter of taste, but also of compatibility of hardware. There are many builds for Redmi 9, but not all of them are stable. The most popular are LineageOS, Pixel Experience (or its forks) and ArrowOS. Each of them has its own characteristics: some are focused on maximum speed, others on the visual similarity to Google Pixel and the presence of all services out of the box.
When choosing a build status, you should pay attention to: Stable (stable) or Nightly (nightly build for testing). For everyday use, it is better to choose proven Stable versions that fix critical bugs with the camera, Bluetooth and sound. It is also important to check which version of Android is at the heart of the firmware, since older versions may not support some modern applications.
| Name of firmware | Basis | Stability | Features |
|---|---|---|---|
| LineageOS | AOSP | Tall. | Minimalism, no Google Apps |
| Pixel Experience | AOSP | Medium | Full copy of Google Pixel |
| ArrowOS | AOSP | Tall. | Lightweight, speed. |
| crDroid | LineageOS | Tall. | A huge amount of customization. |
Where do I look for firmware?
Installation process and initial setup
Once the firmware image and the necessary add-ons (GApps — Google Apps, if not built in) are uploaded to a memory card or internal storage, the main step begins. The TWRP menu needs to format the Data partition, which removes the encryption of the old system, without which the new firmware will not be able to read the data correctly or start.
Next is the Wipe menu, where you select the Dalvik/ART Cache, Cache, System, and Data sections. Don't touch the Internal Storage section if you store installation files there, or you'll have to re-slip them from your computer. After cleaning, go to the Install menu, select the archive with the firmware and swipe to confirm the installation.
It can take 3 to 10 minutes to install, and it displays a process log where the experienced user can see errors. If the process is successful, the Reboot System button will appear. The first run of a clean system usually takes longer than usual, sometimes up to 5-7 minutes, as the applications are optimized and a new file structure is created.
- 🧹 Run Wipe Dalvik, Cache, System, Data.
- 📥 Install. ZIP-Firmware Archives via Install.
- 🔧 If necessary, install GApps as a separate archive.
- 🔄 Restart the system and wait for optimization to complete.
⚠️ Warning: If after installation, the system goes into an endless bootloop, don't panic. TWRP, Run the full Wipe (including Internal Storage if the data isn’t important) and try reflashing or roll back to the backup.
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Use the "Backup" function in TWRP Before installing a new firmware, save Boot, System and Data images to your computer or SD-This will allow you to return to the original state in 5 minutes in case of failure.
Solving common problems and bugs
The transition to custom firmware rarely goes smoothly, especially on devices with MediaTek processors, as in the case of Redmi 9. Users may experience a broken camera, no sound in the headphones or fast battery discharge, often these problems are solved by installing additional patches or highways (magisk modules) that adjust the driver operation.
The problem with Widevine L1 — a common phenomenon that causes Netflix and other streaming services to stop showing content in the HD This is due to a breach of the chain of trust when the bootloader is unlocked. L1 certified method on unlocked bootloader is almost impossible, but there are workarounds through modified APK-file.
If VoLTE or video calls don't work, it's likely that the firmware doesn't have proprietary files from stock MIUI. In such cases, it's recommended to search the forum for a topic dedicated to your model and download a patch that fixes it. Often, enthusiasts upload files or firmware that vendor vendors need to stitch before installing the main system.
Optimization and further maintenance
After a successful launch of pure Android, it is recommended to immediately adjust the energy saving and background activity settings. Unlike MIUI, there is no aggressive “task killer” here, so some applications can waste resources. Go to the battery settings and limit background activity for rarely used programs.
Magisk is the best way to manage superuser rights, if you need them, by hiding root rights from banking apps and anti-cheat games. Regularly updating Magisk and the firmware itself via OTA (if supported by the developer) will ensure the device’s long-term security and stability.
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Pure Android on Redmi 9 gives a second life to the device, removes advertising and speeds up work, but requires a willingness to solve small technical nuances on their own.