I wanted to update my wife's REDMI 5 PLUS (MIUI Global 10.0.22 OEGMIFA, Android 8.1) to MIUI Global 10.2.3 OEGMIXM Android 8.1... I bricked her phone in the process. So I was stuck in bootloop cycle; the phone remained in Mi Recovery mode.
I read an article online, which advised me to use TESTPOINT METHOD and flash the phone with a "particular" Chinese beta ROM. So through fastboot, I used Mi FlashTool 2017 version to flash the phone, and the Chinese ROM was installed. The phone came on having MIUI 9 beta, Android 7.1.1.
I now used Mi Unlock to unlock the bootloader, it gave me 72hrs to try again. I tried again after 72hrs (3 days) and the phone's bootloader was successfully unlocked. So I flashed it again with the Mi FlashTool, using the same MIUI Global 10.2.3 OEGMIXM, Android 8.1, and it was successful.
Note, I flashed it in CLEAN ALL mode (left the bootloader unlocked) if you CLEAN and LOCK it'll fail.