Disclaimer: I am not responsible for your phone if you do anything covered on this page, this page merely documents how I did it for myself.
What am I using?
I’m using Windows 10 for the MIUI unlock tool, Ubuntu 18.04 for fastboot and adb.
This sucks, I needed to dust off my Windows install and visit https://en.miui.com/unlock/ to download a .zip file which contained an executable.
Before being able to unlock it, I needed to wait 72 hours…
Once unlocked I found a recovery-20181012.img file from this file host: https://www.androidfilehost.com/?w=files&flid=283470 which was shared on https://forum.xda-developers.com/poco-f1/development/recovery-twrp-3-2-3-decryption-t3853004
I installed it by pressing power+vol-down for a long time to get into fastboot and using the following command from my Linux terminal
fastboot flash recovery recovery-20181012.img
Booting into Android unfortunately resulted in the recovery being restored to MI-Recovery 3.0, so…
From https://drive.google.com/drive/folders/1QtcAbo5YklB9w-H4PeXEBB0nBoT42fwF I downloaded the DisableForceEncryption_Treble.zip file and placed it along with therecovery-20181012.img file onto the phone’s storage.
(The twrp-18.104.22.168-beryllium-20180831.img file in the GDrive wasn’t decrypting the storage in TWRP, so I didn’t use that anymore.
Boot into TWRP
Formatted data, flashed the DisableForceEncryption_Treble.zip file.
Flashing DisableForceEncryption_Treble.zip actually installed Magisk as well and rooted the device in the process.
Run a backup
At this point I made a backup of all partitions to my MicroSD card to capture the current OS, booted into the OS, downloaded some apps, registered the device again in MIUI, made some changes and tested a restore.
First do a standard wipe (data, cache & Dalvik are standard) and then do the restore of all partitions (excl. storage).
This resulted in a bootloop, at least TWRP is still there..
Install MIUI 10 Global Stable
On https://forum.xda-developers.com/poco-f1/how-to/xiaomi-poco-f1-unlock-bootloader-custom-t3839405 I found http://bigota.d.miui.com/V10.0.4.0.OEJMIFH/miui_POCOF1Global_V10.0.4.0.OEJMIFH_ef67c4052e_8.1.zip
It started booting into Android again and encrypting the device 🙂
Recovery also restored
Unfortunately this also set me back to the MI-Recovery 3.0, at least the device was still unlocked, so back to fastboot it was.