Owners of the legendary Xiaomi Mi 9T (known in China as the Redmi K20) often wonder about extending the life of their device. Despite the fact that official support for the model by Xiaomi has already been completed, the enthusiastic community continues to release current versions of the operating system. The transition to Android 12 allows not only to get a fresh interface, but also to ensure the relevance of security levels, which is critical for the preservation of personal data.
The upgrade process is not trivial and requires care, since the standard Settings menu will no longer offer new versions of the software. You will have to choose between installing custom firmware or searching for global versions of MIUI 12.5 based on the twelfth version of the Android. In any case, before starting any manipulations, you need to clearly understand the risks and prepare the device for interference in the system partition.
This article is intended to be a comprehensive guide for those who want to reanimate their smartphone.We will look at proven methods, necessary tools and pitfalls that you can face.If you are willing to risk the guarantee (which is likely already expired) for a new life gadget, then carefully study each step.
Situation analysis: official support and reality
The situation with the software for Redmi K20 / Mi 9T The smartphone came with Android 9, received an update to Android 10 and 11 within the framework of MIUI However, the official update cycle for this model has ended, and Xiaomi has not released Android 12 for it in the global stable branch. OTA-You will not receive the desired version.
However, the Snapdragon 730 (Pro version 855) processor architecture allows modern versions of the operating system to run smoothly. Enthusiasts from the XDA Developers and 4PDA forums have created a variety of ports, including LineageOS, Pixel Experience and adapted versions of MIUI. These solutions become the only bridge to Android 12.
⚠️ Note: Installing unofficial firmware or flashing regional versions (e.g., Chinese global) may result in the blocking of your Mi Account or loss of warranty if it is still valid.
It is important to distinguish between “update” and “flashing”: an update usually saves user data, whereas the transition to custom build Android 12 most often requires a complete cleanup of the device’s memory (Wipe Data), so the first and most important step is to back up all important information.
Preparation of the device and necessary tools
Before we take action, we need to build tools. USB-The cable and the computer that's working may not go as planned. The cable has to transmit data, not just charge, because we're going to work with Fastboot and Recovery modes.
The second critical point is unlocking the bootloader. To install any version of Android 12 on the Mi 9T, an unlocked bootloader is mandatory. The official procedure requires submitting an application through the Mi Unlock Tool app and waiting 7 to 168 hours (usually 168 hours or 7 days).
☑️ Checklist for firmware preparation
You will also need to download and install the Platform Tools package on your computer (ADB Without these gates, Windows or Linux will not be able to "see" the smartphone in debugging mode. Make sure that the phone itself has a "Developers" menu item activated. USB-debugging.
Don't forget to check the integrity of the downloaded firmware file. If you're downloading an image from a third-party resource, check the checksum (MD5 or SHA) if provided by the author. A damaged file can turn the phone into a brick or cause a cyclic reboot.
Method 1: Installation of custom firmware (Custom ROM)
This is the most reliable way to get exactly Android 12 (or even newer) on your Mi 9T. Custom firmware such as LineageOS 19, Pixel Experience or Evolution X is based on pure Android and lacks the heavy MIUI interface, which often has a positive effect on performance.
The process begins with the installation of custom Recovery, most often using TWRP (Team Win Recovery Project). After loading into TWRP (pressing the power and volume button up), you need to clean the Dalvik / ART Cache, Cache, System and Data partitions.
Then, through the Install menu, the TWRP selects a downloaded zip archive with firmware, which takes 3 to 10 minutes to install, while the system replaces system files, libraries and the kernel with new versions compatible with Android 12.
⚠️ Note: When transitioning from MIUI On custom Android 12, all data will be destroyed. If you don't backup photos and contacts, it will be impossible to restore them.
Once you install the firmware itself, it is often recommended to flash Google Apps (GApps) immediately if it is not built into the ROM to access the Play Market. Without this step, you will get a system without the Google Apps and Services Store.
What are GApps and why do they need them?
Method 2: Global versions of MIUI based on Android 12
There is an alternative for those who don’t want to part with the MIUI shell. Some regional versions (such as India or Europe) for similar models could get an updated stable build. However, for the Mi 9T, the situation is complicated: the official MIUI 12.5 is often based on Android 11.
However, there are MIUI 12.5 Enhanced Edition ports that can formally carry under-hood changes similar to Android 12, or be modified by builds.
To do this, the phone is put into Fastboot mode (pressing power and volume down, a bunny appears), connects to a PC. A firmware script is launched through the command line. It is important to use the version of Fastboot-rum that is designed for your region or is global (Global) to avoid problems with banking applications.
| Parameter | Custom firmware (Custom ROM) | Official / MIUI Ports |
|---|---|---|
| Basis | Pure Android (AOSP) | MIUI shell |
| Android version | 12, 13, 14+ | More often than 11, less often 12 |
| Stability | Depends on the builder. | High (official) |
| Camera. | Requires settings (GCam) | Sweet, stable. |
If you want speed and novelty, choose a custom. If you want stability of calls and native camera out of the box, look for current MIUI ports.
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After installing the new system, let the phone lie on charge for 15-20 minutes on the first turn on, and the system optimizes applications, which can temporarily slow down.
Fixing errors and problems after updating
The first run after installing Android 12 can take up to 10 minutes. If the phone is stuck on the logo (bootloop), don't panic. Often, re-entering Recovery and clearing the cache (Wipe Cache Partition) helps. If that didn't help, it may be that the firmware file was corrupted or incompatible with your board revision.
Another common problem is the broken WideVine L1. This is the DRM layer you need to watch Netflix and other streamings in HD. When you unlock the bootloader, the level often drops to L3, and HD content becomes unavailable. It is extremely difficult to return L1 on an unlocked bootloader to the Mi 9T, sometimes impossible without special patches.
And users may experience a rapid battery drain in the early days, which is normal: system and applications must re-index and learn a new energy-saving algorithm, usually after 3-5 days, autonomy returns to normal.
⚠️ Note: If the firmware stopped working NFC (Pay by phone, check the security status in the Mi Credit app or settings NFC. Payment may not work at all on custom firmware due to lack of Google Pay SafetyNet certification.
In case of serious errors, the return to the factory firmware (Stock ROM) is possible only through Fastboot mode and the Mi Flash Tool program. This will completely delete all data and return the phone to the state of "from the store."
Optimize and customize Android 12 on Mi 9T
After successfully installing the new system, you should get into fine-tuning. Android 12 brought a new Material You design that dynamically changes the colors of the interface depending on your wallpaper. Go into the theme settings and experiment with the palette.
Pay special attention to battery settings. The new system has changed the logic of the background processes. Go through the list of applications and limit background activity for those programs that you do not need constantly (for example, delivery of food or taxi).
To improve the quality of your photos, especially if you have switched to a cast, install the Google Camera port (GCam). For the Snapdragon 730/855 processor, there are stable versions that squeeze the maximum out of the Mi 9T arrays, providing excellent night mode and HDR+.
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The main secret of a long life of the updated smartphone is not to overload it with unnecessary launchers and antiviruses, the built-in protection of Android 12 is quite sufficient.
Remember to update apps regularly through the Play Market and keep an eye on new firmware releases if you use a caste.Developers often release patches that fix Bluetooth bugs or improve camera performance.