F, using your photo that I flipped over, I added how mine was originally. Like was pointed out, that 12v from the battery should get thru the main breaker (with the small black button) and on inside to the battery cutoff. The 12v comes back to the copper bus which powers other things thru other breakers. Your wiring looks different, so maybe the wiring to and from the cutoff switch has been tampered with??
Hyper Lite was sold
2017 F-250 4x4 6.2L Gas
I can't fix everything, but I can make it so nobody else can