Hacking Switch error at start up after downgrading with ChoiDujourNX. help

[askara]

i was on 8.0.1 with atmosphere but i downgraded to 7.0.0 with ChoiDujourNX, now my switch go into a error screen(atmosphere) and wont boot. what do i do?

 

[thesjaakspoiler]

My French isn't that good though but someone here got the same error and
mentioned that he messed up his prod.keys file and was missing the first line in it :
http://www.logic-sunrise.com/forums/topic/86135-resolu-switche-deja-brickee/
We all moved to 9.0 so maybe something broke in the automated key derivation for older firmwares.