[help] Upgrade To Miui 8 From Miui 7 And Relock Bootloader.

Apr 10, 2016
At first, sorry about my english.
Hello everyone.
My redmi note 3 pro is using miui 7. Now, i want to upgrade it to miui 8 to reslove some problems.
But my note 3 pro unlocked bootloader unofficial and i used to delete firmware-update folder in eu rom to prevent to relock bootloader.
Now i want to clean-flash miui 8 on it and unlock bootloader by official from xiaomi.
Which way can i use to safe and clean flash? EDL mode or mi flash?
Thank for reading.
Have a nice day :).