https://www.youtube.com/watch?v=nSsqnn0RXr4Some latin american youtuber just caused all his followers attempting to follow his guide to brick because they used his otp.bin during their installation of a9lh, which he included in his pack of downloads for downgrading use.
The comments are hilarious if you speak spanish.
For the uninitiated, otp.bin is unique to each console, and using any otp.bin other than your own will guarantee a brick.
Noone should downgrade. It's bad.
;^)