The Xiaomi Mi 8 SE is one of the most popular smartphones of 2018, still in use today thanks to powerful hardware and community support. However, over time, official updates stop coming out, and users face slowdowns, bugs or the desire to install custom firmware. The device’s firmware can solve these problems, but requires careful attention: a bug at any stage can turn the phone into a brick.
In this guide, we will discuss all the current ways to install the Mi 8 SE firmware (codename sirius): from the official update via MIUI Updater to install custom firmware through TWRP and Fastboot. We will focus on unlocking the bootloader, choosing the right firmware version and solving typical errors. If you are a beginner, start with the official methods. Experienced users will find here the nuances of working with ADB, patching boot.img and alternative recaveries.
Before you start, consider that the firmware of the smartphone will void the warranty (if it is still valid), and informal firmware may contain vulnerabilities, and all manipulations you perform at your own risk.
1. Firmware Preparation: What to Do Before Starting
Xiaomi Mi 8 SE firmware is a multifaceted process, and its success depends on 80% of the correct preparation. The first thing to check is the current firmware version and the status of the bootloader.
- Go to Settings → About → MIUI version and write down the current version (e.g. MIUI 12.5.4 Stable).
- Turn off the phone, then press Volume Down + Power to log in to Fastboot. If you see the word Device unlocked, the bootloader is already unlocked.
If the bootloader is locked (device locked), it will have to be unlocked through the official Mi Unlock Tool, a process that takes up to 720 hours (30 days) of waiting for new Xiaomi accounts, so plan ahead.
⚠️ Attention: Unlocking the bootloader erases all data from the device, including photos and apps. make a backup through Settings → Additionally. → Backup and reset or by using Mi PC Suite.
Also prepare:
- 🔌 Charged smartphone (at least 60% of the battery).
- 💻 Windows computer 10/11 (Fastboot and Mi Unlock Tool).
- 🔗 Cable USB Type-C (original or certified).
- 📁 firmware corresponding to the sirius model (download only from official sources: MIUI Download or XDA Developers).
Make a backup copy of the data|Check the version. MIUI|Charge the phone before 60%+|Download firmware for the Sirius model|Install drivers ADB/Fastboot PC-only-->
2 Unlock the bootloader on Xiaomi Mi 8 SE
Without an unlocked bootloader, you can only install official firmware via MIUI Updater or Recovery. For custom firmware (LineageOS, Pixel Experience) and TWRP, unlocking is mandatory.
The process consists of three stages:
- Linking the Mi Account to the device:
- Installation of Mi Unlock Tool:
Unlocking
- 🔓 Connect your phone in Fastboot mode (clip Volume Down) + Nutrition).
- 🖥️ Launch the Mi Unlock Tool, log in to your account and follow the instructions.
If the update is stuck on the MI logo for more than 15 minutes:
- 🔄 Force the phone to restart (clip the power for 10 seconds).
- 📱 If the device is not turned on, try logging into Recovery (clip Volume Up). + Power) and select Wipe Data (this will erase all data!).
- Custom software firmware: