[Xiaomi Mi MIX  Guides, News, & Discussion] satishp:
This is for people who have received their phone with a pre-installed Vendor ROM (MIUI Global Stable 8.0.8.0) and wants to switch to the Unofficial EU ROM. In my opinion, the EU ROM is currently the best ROM without any Chinese bloatware or popups until Xiaomi decides to release an actual Global ROM.

For those who are already on a China Stable ROM, there is already an excellent guide to install TWRP, ROOT, compiled by [MENTION=4233496]underlines[/MENTION]. This is only intended for switching from a Vendor ROM as I wasn't able to switch from a Vendor ROM to an official build using the previous guide. You need to be on an official build to be able to use TWRP and flash the EU ROM.

EDIT : The reason why I have mentioned to flash an official build at first is because, TWRP can be unresponsive with some Vendor ROMS. You'll be able to boot TWRP but touch would be frozen. I've tried with both versions of TWRP and it wouldn't work with the Vendor ROM installed on my device. TWRP over the Vendor ROM may work for some users.. For some builds like the one which came installed on my phone, it may not work. If TWRP works for you without being on an official build, you can skip the part where you have to flash an official ROM.

1. You need to have an unlocked bootloader. Please follow instructions on the other guide on how to do this.

2. You need the older version of MiFlash found on this link. Thanks to [MENTION=3169046]Thorin78[/MENTION] for this link.

3. Download and extract fastboot Stable or Dev ROM and extract ROM folder to the C:\ Drive. This is because MiFlash may show a "cannot find file" error if you have a lot of subfolders. To avoid this, its best if the folder is C:\ROM Folder.

4.In the older version of MiFlash, click advanced and change the fastboot script location to the flash_all.bat in your unzipped rom folder.

5.Connect your phone in fastboot mode, click "Refresh" in MiFlash. Once your phone is detected, click "Flash" and it should now successfully flash the official ROM of your choice.

If you wish to be on a Xiaomi Official Stable or Dev ROM, Stop here! If you wish to continue installing the EU ROM proceed with the steps below.

6. Now that you have successfully flashed Official Stable or Dev ROM, use Minimal ADB and flash TWRP RC2 using the instructions in the other guide.

7. Once you are in TWRP, Swipe right to allow System Modifications and copy the forced encryption disabler using MTP. Flash this file to ensure that there are no bootloops.

8. After this step, go to WIPE, Format Storage, type "yes" and then Reboot Recovery. Copy SuperSU and EU ROM to storage and flash. Phone may take a few minutes to boot up and you will successfully boot the EU ROM.

For everything else, please follow the guide posted by underlines.

TWRP EU RC2 works with the China Dev ROM as well. Once you Swipe to Right to allow modifications, don't forget to flash the latest dm-verity and forced encryption disabler script from here. This is to prevent the device going into a bootloop.

These are the steps I followed and I am on EU ROM. Hope this helps people who wish to switch to the EU ROM from the Vendor ROM.