How to flash Xiaomi Mi Mix 2S: official and custom firmware

Xiaomi Mi Mix 2S is the flagship smartphone of 2018, which is still relevant thanks to powerful hardware and support for custom firmware. However, over time, official updates from Xiaomi stop coming out, and users face slowdowns, bugs or the desire to install a fresh version of Android. The firmware of the device can solve these problems, but requires careful attention: a mistake at any stage can turn the phone into a “brick”.

In this guide, we will take a look at all the current ways to run the Mi Mix 2S firmware, from official updates via MIUI Updater to custom firmware installations like LineageOS or Pixel Experience. We will focus on unlocking the bootloader, a must-have for most methods, and how to avoid common bugs such as anti-rollback or failures when checking boot.img.

If you are a beginner, we recommend starting with the official methods (sections 2–3). For experienced users, instructions on installing TWRP and custom firmware (sections 4–6) will be useful.

1. Firmware Preparation: What You Need to Know Before Starting

The Xiaomi Mi Mix 2S firmware is a process that requires preparation, and without it, you risk getting a bricked device (a broken phone) or losing data.

• 🔋 Battery charge: Make sure the charge level is at least 60%. When discharged during firmware, the device may shut down, which will cause a failure.
• 📱 Backup: Save all important data (photos, contacts, messages) to your PC or cloud. /data.
• 🔑 Unlocking the bootloader: To install custom firmware or TWRP You need to unlock the bootloader. This is an official procedure from Xiaomi, but it resets the device to the factory settings.
• 🖥️ Drivers and tools: Install Mi Unlock Tool, drivers ADB/Fastboot Download the required firmware (links in the following sections).

Important: Xiaomi Mi Mix 2S has anti-rollback protection. If you install a MIUI version older than the one already on the device, the phone will lock. Check the current version in Settings → About Phone → MIUI version and compare it to the firmware version you are going to install.

Also, look at the model of the device. Mi Mix 2S was released in several versions:

⚠️ Note: Firmware from another model (e.g., Chinese to global) can cause network or camera problems. Always check the code name (polaris) and firmware region.

2. Official firmware via MIUI Updater (without unlocking)

The safest way to upgrade the Mi Mix 2S is to use the built-in MIUI Updater, which does not require unlocking the bootloader and is suitable for installing stable or beta versions of MIUI.

• 📲 The device is not rooted.
• 🔄 Current firmware is not modified (no custom recovery or core).
• 🌐 There is a stable internet connection (Wi-Fi is recommended).

Instructions:

1. Open Settings → About the phone → System update.
2. Click on the three dots in the top right corner and select Select Service Pack.
3. If the update is available, download it. If not, download the full firmware package (.zip) from Xiaomi's official website and select it manually.
4. Confirm installation. The phone will reboot and update automatically.

If the update is “hanging” during the verification phase, try:

• 🔄 Restart the device and try again.
• 📡 Connect to another Wi-Fi network.
• 🗑️ Clear the update cache in Settings → Annexes → Application management → Updating the system → Warehouse → Clear the cache.

⚠️ Note: If a Couldn't verify update error appears during the update, it may mean that the firmware is damaged or not suitable for your model (MD5).

3. Firmware via Fastboot (official MIUI)

If MIUI Updater doesn’t work or you want to install the firmware from scratch (like after a reset), use Fastboot mode.This method requires a PC and unlocked bootloader, but allows you to install any official version of MIUI, including Global Stable, China Stable, or Developer.

Download the desired firmware from the official website (choose the Fastboot version) and unpack the archive into a folder on your PC.

• 🖥️ Mi Flash Tool (download here).
• 🔌 Cable USB Type-C (preferably original).
• 🔑 Unlocked boot loader (instructions in the next section).

Step-by-step:

1. Turn off the phone and press Volume Down + Power to enter the Fastboot (the image of a hare in a hat-eared will appear).
2. Connect the device to the PC.
3. Launch the Mi Flash Tool, press Select and point the path to the unpacked firmware.
4. At the bottom, select firmware mode: Clean all – complete cleaning (recommended when changing the version of MIUI); Clean all and lock – cleaning + lock the bootloader (use if you want to return the official status); Save user data – data storage (does not always work correctly).

Flash

If the Mi Flash Tool is flash not done or critical partition error, try:

• 🔄 Reinstall Fastboot drivers (use Google) USB Driver).
• 🔌 Connect the phone to another USB-port (preferably) USB 2.0).
• 📁 Download the firmware again (possibly the archive is damaged).

4. Unlock the bootloader on Xiaomi Mi Mix 2S

Without bootloader unlocking, you won’t be able to install TWRP, custom firmware, or even official MIUI via Fastboot in Clean all and lock mode. Xiaomi allows unlocking, but the process requires a Mi Account and wait (usually 7-15 days).

You'll need:

• 📱 Phone with an associated Mi Account (Settings should be enabled in the settings) → Additionally. → Developer → Mi Unlock status).
• 🖥️ PC with Mi Unlock Tool installed.
• 🔌 Cable USB Type-C.
• 📡 Stable Internet connection.

Instructions:

1. Turn on Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times.
2. Back to Settings → More → For developers and activate: Debugging over USB OEM Unlock (could be called Status Mi Unlock)

Connect the phone to the PC, confirm the debugging permission.

Mi Unlock Tool

Mi

Couldn’t unlock. Wait for 72/168 hours

After successful unlocking, the phone will restart and reset to factory settings.

⚠️ Note: If you previously blocked the bootloader through Clean all and lock in the Mi Flash Tool, it can take up to 30 days to unlock. Also note that after unlocking some features (such as Mi Pay or Find Device) may stop working.

5. Installation of TWRP and custom firmware

If you want to install LineageOS, Pixel Experience or other custom firmware, you will need TWRP – custom Recovery. For Xiaomi Mi Mix 2S, the current version is TWRP 3.7.0 (or newer) from the developer mauronofrio.

Warning: Installing TWRP and custom firmware can lead to:

• 🚫 Loss of warranty (if it is still valid).
• 📵 Camera or mobile network problems (some firmware doesn't support all Mi Mix features) 2S).
• 🔒 Locking the device in case of an error (for example, if the firmware is not compatible with the anti-rollback version).

Instructions for installing TWRP:

1. Download the last one. TWRP for polaris from the official website (file) twrp-3.7.0_9-0-polaris.img).
2. Download. disable_dm-verity_forceencrypt (avoiding encrypted /data post-fix).
3. Connect your phone to your PC in Fastboot mode (clip Volume Down + Power).
4. Open the command line in the folder with ADB/Fastboot Next Post:Fastboot Flash Recovery twrp-3.7.0_9-0-polaris.img fastboot boot twrp-3.7.0_9-0-polaris.img The phone will reboot to TWRP.
5. In TWRP, go to Wipe → Format Data, type in yes and confirm (this will remove encryption).
6. Copy. disable_dm-verity_forceencrypt.zip on your phone and install it via Install.
7. Reboot to TWRP (not in the system!) Now you can install custom firmware.

For custom firmware installation (e.g. LineageOS 20):

1. Download firmware (.zip) and, if necessary, GApps (for example, NikGapps).
2. Copy the files onto your phone.
3. In TWRP, run Wipe → Advanced Wipe and mark Dalvik, Cache, System, Data.
4. Install firmware, then GApps (if you need Google services).
5. Reboot to the system. The first launch can take 10-15 minutes.

💡

If the camera does not work after installing the custom firmware, download and swipe through the TWRP module ANX Camera or GCam with support for Mi Mix 2S. See the links on the XDA-Developers forum.

6. Solving common firmware errors

Even if you follow the instructions, you can still get errors, and here are the most common problems and solutions for the Xiaomi Mi Mix 2S:

If your phone has turned into a hard brick, try:

1. Connect the device to the PC in EDL mode (clip Volume up + Volume down + Power on the phone turned off).
2. Use the Mi Flash Tool with firmware in.tgz format (you can download it on Xiaomi Firmware Updater).
3. Select Clean all mode and go through. If your PC doesn't see the device in EDL, you'll need an authorized Xiaomi account (see service center).

💡

If after firmware the phone is stuck on the logo MI, Try to go to Fastboot (Loudness Down). + Food, and re-stitch. If it doesn't work, use it. EDL-regime.

7.How to return the official firmware after custom

If you’ve experimented with custom firmware and want to return stock MIUI, follow this instruction. The process involves locking the bootloader, which will return the device to official status (but reset all data).

You'll need:

• 📱 Unlocked loader.
• 🖥️ The official Fastboot firmware for your model.
• 🔧 Mi Flash Tool.

Steps:

1. Download the official Fastboot firmware from Xiaomi’s website (choose the same version as before custom firmware, or newer).
2. Unpack the archive in a folder without spaces and Cyrillic.
3. Turn off the phone and press Volume Down + Power to log into the Fastboot.
4. Connect the device to your PC and start the Mi Flash Tool.
5. Select the firmware folder and Clean all and lock mode.
6. Press Flash and wait until it's finished. The phone will reboot and it'll be like new.

After that:

• 🔒 The bootloader will lock and you will not be able to install custom firmware without re-unblocking.
• 📱 All data will be erased, including internal memory.
• 🔄 To update through MIUI Updater, you will have to wait 7-30 days (depending on Xiaomi policy).

FAQ: Frequent questions about the Xiaomi Mi Mix firmware 2S