There are people who have upgraded from that ROM directly to 8.5.1 without problem by updater. You would not lose your data because you are not deleting the internal memory
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First look this tutorial http://en.miui.com/thread-251450-1-1.html
Second update twrp to aqua v8
https://www.androidfilehost.com/?fid=24665539028713602
Third update from twrp to 6.12.22 rom
Enviado desde mi MI 4S mediante Tapatalk
Only english?
I can find the solution in Spanish. That's because you had the device search option turned on, and sometimes it gives that problem. Lost device
Enviado desde mi MI 4S mediante Tapatalk
Put into memory phone two twrp, for miui 7, and for miui 8.
Then flash twrp zip for miui 7 by mi flash, restart recovery Mode.
On recovery set to install by Img, and choose twrp 3.0.2.0 aqua. Restart sistem
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