Download Xiaomi Mi Mix 2S Firmware (polaris): Fix System Lag & Battery Drain
This guide provides the complete firmware collection for the Xiaomi Mi Mix 2S (polaris). If you’re experiencing system lag, battery drain, or a bricked device, our verified download links and detailed flashing instructions will help you restore your phone’s functionality. The Mi Mix 2S, featuring a Snapdragon 845 chipset and a 5.99-inch FHD+ display, is a flagship device from 2018 with a sleek ceramic design. Software issues can affect its performance, and this guide will help you resolve them. Note: This article is for the polaris codename (Mi Mix 2S), not to be confused with other Mi Mix models like Mi Mix 2 (chirion) or Mi Mix 3 (perseus).
⚠️ Essential Pre-Flash Checklist
Flashing can lead to errors if not done correctly. Complete this checklist to ensure a smooth process. All data will be wiped, so a backup is critical.
- ✅ Full Data Backup: Save photos, contacts, and files to Mi Cloud, Google Drive, or a PC to prevent data loss.
- ✅ Charged Battery: Ensure your Mi Mix 2S has at least 60% battery to avoid interruptions during flashing.
- ✅ Windows PC: The Mi Flash Tool requires a Windows operating system.
- ✅ Original USB Cable: Use a high-quality USB cable for a stable connection to your PC.
- ✅ Unlocked Bootloader: Flashing requires an unlocked bootloader. Use the official Mi Unlock Tool (expect a 7-15 day waiting period).
- ✅ Required Software: Install the latest Mi Flash Tool and Xiaomi USB Drivers.
Understanding the Firmware: Types and Regions
Selecting the correct firmware is crucial to avoid bricking your Mi Mix 2S (polaris). The polaris variant is specific to the Mi Mix 2S with the Snapdragon 845 processor.
- Fastboot ROM (.tgz): A full factory image for Mi Flash Tool, ideal for unbricking or reverting to stock MIUI.
- Recovery ROM (.zip): Used with custom recoveries like TWRP for installing custom ROMs like Xiaomi.eu.
- Region Codes:
- CNXM: China version, optimized for local networks but may lack Google Play services.
- MIXM: Global version with Google services and multi-language support.
- RUXM: Russia-specific firmware with localized apps and settings.
- EUXM: Xiaomi.eu version, a debloated MIUI ROM with Google services and multi-language support.
Official Firmware Downloads for Mi Mix 2S (polaris)
These firmware files are sourced from Xiaomi’s official servers or trusted repositories for reliability and security. Choose the latest version for your region to ensure optimal performance. Ensure you download ROMs for the polaris codename. Note: The Russia ROM is incorrectly labeled as “India” in the provided link; it is for the Russia region (RUXM).
| Region | MIUI Version | Android | Release Date | Download Link |
|---|---|---|---|---|
| China (CNXM) | V12.5.1.0.QDGCNXM | 10.0 | 2021-07-07 | Fastboot ROM |
| Global (MIXM) | V12.0.3.0.QDGMIXM | 10.0 | 2020-12-28 | Fastboot ROM |
| Russia (RUXM) | V12.0.2.0.QDGRUXM | 10.0 | 2020-12-15 | Fastboot ROM |
| EU (EUXM) | V12.5.1.0.QDGCNXM | 10.0 | Unknown | Recovery ROM |
TWRP Recovery for Mi Mix 2S (polaris)
To flash custom ROMs or perform advanced tasks, install the TWRP custom recovery specific to the Mi Mix 2S (polaris).
- TWRP Recovery: TWRP-3.3.2B-0302-XIAOMI_MIX2S-CN-wzsx150 – Use this to flash the Xiaomi.eu ROM or other custom ROMs. For newer versions, check TWRP’s official site or XDA Forums.
How to Install TWRP:
- Download the TWRP .img file and rename it to
recovery.img. - Boot your Mi Mix 2S into Fastboot mode (Volume Down + Power).
- Connect to your PC and open a command prompt.
- Flash TWRP by running:
fastboot flash recovery recovery.img. - Boot into recovery:
fastboot boot recovery.img.
Warning: Do not use a TWRP image for other devices (e.g., chirion or perseus), as it will brick your polaris device.
Recommended Custom ROMs
For users dealing with bloatware or seeking a smoother experience, the Xiaomi.eu ROM leverages the Mi Mix 2S’s Snapdragon 845 for a refined MIUI experience. The polaris variant has strong custom ROM support due to its flagship hardware.
- Xiaomi.eu ROM: V12.5.1.0.QDGCNXM Based on Android 10 – Offers a lightweight, optimized MIUI experience with Google services.
- LineageOS: Check LineageOS or XDA Forums for official or unofficial builds like LineageOS 18.1 (Android 11), providing a clean Android experience with excellent performance.
How to Flash: Step-by-Step Instructions
Choose the flashing method based on your firmware type: Fastboot for official .tgz files or Recovery for custom .zip files.
Method 1: The Fastboot Method (Official Stock ROMs)
- Unzip the Firmware: Extract the .tgz file using 7-Zip to obtain a folder with an “images” subfolder and flash scripts.
- Launch Mi Flash Tool: Open the Mi Flash Tool with administrator privileges on your Windows PC.
- Enter Fastboot Mode: Power off your Mi Mix 2S, then press and hold Volume Down + Power until the Fastboot logo appears.
- Connect to PC: Plug your phone into your PC using the USB cable.
- Load Firmware: In Mi Flash Tool, click “select” and choose the extracted firmware folder. Click “refresh” to detect your device.
- Choose Flash Option: Select “clean all” for a complete reset (recommended for stability). Avoid “clean all and lock” unless you’re certain of the ROM’s region compatibility.
- Start Flashing: Click “flash” and wait 5-10 minutes. Do not disconnect the phone.
Troubleshooting Tip: If Mi Flash Tool fails to detect your Mi Mix 2S, try reinstalling the Xiaomi USB Drivers or switching to a USB 2.0 port for better connectivity.
Method 2: The Recovery Method (Custom ROMs)
- Install TWRP: Ensure TWRP is installed using the provided TWRP image or a newer version from TWRP’s official site.
- Transfer ROM: Copy the .zip ROM file (e.g., Xiaomi.eu) to your phone’s internal storage or an SD card.
- Boot into Recovery: Power off your phone, then press Volume Up + Power until the TWRP logo appears.
- Wipe Data: In TWRP, go to “Wipe” > “Advanced Wipe” and select Dalvik/ART Cache, Cache, and Data. Swipe to confirm.
- Install ROM: Return to the main menu, tap “Install,” select the .zip file, and swipe to flash.
- Reboot: Reboot to system after installation completes.
After the Flash: First Boot and Setup
The first boot after flashing may take 10-15 minutes as the system initializes. Don’t interrupt if it seems stuck on the Mi logo. Once booted, follow the setup wizard and restore your data from your backup.
Device-Specific Q&A for the Mi Mix 2S (polaris)
- Q1: Why does my Mi Mix 2S experience system lag? A: System lag can result from bloatware or heavy apps taxing the Snapdragon 845. Flashing the latest China ROM (V12.5.1.0) or the Xiaomi.eu ROM can improve responsiveness.
- Q2: How can I fix battery drain on my Mi Mix 2S? A: Battery drain may stem from background processes or outdated firmware on the 3400mAh battery. Flashing a clean stock ROM or the debloated Xiaomi.eu ROM can optimize power efficiency. Custom ROMs like LineageOS 18.1 are reported to improve battery life.
- Q3: Will the Mi Mix 2S receive Android 11 or newer? A: The Mi Mix 2S is officially capped at Android 10 with MIUI 12.5. For Android 11 or newer, consider custom ROMs like LineageOS 18.1, available for polaris on XDA or LineageOS’s official site, offering excellent performance and feature support.
- Q4: I flashed a ROM for chirion or perseus on my polaris device and it’s bricked. What do I do? A: If your device is in EDL mode (Qualcomm HS-USB QDLoader 9008), use Mi Flash Tool with the correct polaris Fastboot ROM (e.g., V12.5.1.0.QDGCNXM). Select “clean all” to restore the device. Seek help on XDA Forums if issues persist.
