Step 5 – Type in the following command and press Enter.
adb reboot bootloader
Step 6 – Wait for your phone to boot into bootloader mode. You can boot your phone in bootloader mode by pressing and holding Volume Up + Power key.
Step 7 – Once your phone is in bootloader mode, type in the following command and press Enter.
fastboot flash recovery twrp-3.2.3-0-polaris.img
Step 8 – After the recovery is flashed, enter the following command. But right after the phone power offs, press and hold Power button as well as Volume Up button so that the phone boots into TWRP and it patches itself. Otherwise, you would have to flash TWRP again.
That’s it! the TWRP recovery is now installed on your Xiaomi Mi Mix 2S. You can enter Recovery Mode (TWRP recovery) by pressing and holding the Volume Down + Power keys together.
Backup and Other Important Tips
Done with the USB drivers? Perfect. The tutorial is on the next page, but first, please take a look at the following tips and important points you need to take care of. These are important, as we don’t want anyone losing their personal data or apps.
Always backup your important data that you might need after you install a new custom ROM, an official software update or anything else. Make a backup for just in case, you never know when anything might go wrong. Read: How to Backup Android Apps, Text Messages, WhatsApp, Call History.
Xiaomi users can also back up data using Xiaomi Mi PC Suite to your computer. Mi PC Suite helps you to move data across different Android devices i.e moving Xiaomi Mi 5 backup data to Samsung Galaxy S8.
If you already have a custom recovery (ClockworkMod, TWRP etc.) installed on your phone, we strongly recommend a backup using that as it creates a complete image of your existing phone set up. [Tutorial: How to Backup Android Phone using TWRP]
A few more optional tips that you should remember:
1. Having problems connecting your Android phone to the computer? You need to enable USB debugging mode. See here: How to Enable USB Debugging — for Gingerbread, Ice Cream Sandwich, Jelly Bean, KitKat, Lollipop, Marshmallow and Nougat.
2. Make sure your Android device is charged up to 80-85% battery level. This might help you: How to Check Battery Percentage. Why? Because, if your phone goes off suddenly while installing a custom ROM, flashing an official firmware update or installing mods etc. — your phone might get bricked or go dead permanently. No one wants that, right?
3. Most of the tutorials and how-to guides on Team Android are for factory unlocked Android phones and tablets. We recommend NOT to try our guides if your phone is locked to a carrier, unless we have specified the carrier name or device model.
If you have any queries or you are facing problems, reach us through the comments and we will get back to you.