How to upgrade to Andoid 7.0:
Install MIUI 6.12.22 before updating to Android 7.0..
Select zip in Updater - menu - select zip
Unlock your bootloader again on Mi4C, Mi4S, MiNotePRO
(check your bootloader status by command "fastboot oem device-info")
Install TWRP for 7.0 via fastboot "fastboot...