the only thing i can think abt is the lever disconnect inside the trailer. did u switch something in there?
do you have lights on or off of shore power? what i'm trying to ask here is if ur battery is dead. if u switch to shore power, u lights should work even if the battery is dead. if they don't work, i would check the breaker panel for a tripped breaker. i would also see if the converter has somehow come unpluged form an outlet.
i'm not firmiliar with ur rig but these are universal.
the breaker panel will look similar to ur home. there should be a fuse pannel as well but this is the dc side.
the converter is a metal box with a fan on it. usually located in some hidden away place...ie cargo area, under stove... the converter is responsible for supplying electricity for the lights, control circuits, etc when ur plugged into shore power. it also keeps the battery charged.
when u disconnect from shore power, the convertor becomes unplugged, or throws a breaker, u are switched to ur battery.
in a word, if ur converter is throwing a breaker, u need to find out why.
what i would need to know is if ur battery is ok and if u have lights when off shore power. if u haven't already found the problem, maybe i can help u trouble shoot it. u never know, someone that knows something may also pop in and lead u right to ur problem.