Took me 3+ weeks but I got it going on Mi Mix3
If anyone has problems this is how I solved it.
I tried Linux mint (my main os), win7 and win10 home - didn`t work
Worked with win10 enterprise and good internet (>1mb/s)
0. Log in to mi account on your phone
- Go into phones developer options and allow usb debigging and OEM unlocking. I also had "install via usb" or something enabled.
- https://c.mi.com/thread-3221402-1-1.html Run as admin and let it do its thing.
- https://en.miui.com/unlock/download_en.html download, extract and run as admin (batch_unlock) and do what it says.
If miui servers are working ok, this should unlock your phone. I didn`t have to wait at all (some have to wait 4+days to unlock). First time I tried it in win10e, miui servers were down for a week or so. - https://github.com/ubports/ubports-installer/releases/tag/0.8.8-beta download for windows and run as admin. This one needs internet>1mb/s I tried it with other phones hotspot (100kb-250kb/s) and it didnt work.
Hope this helps someone.
I`m not a programmer or anything like that.
I am just an open source enthusiast