Not sure what your rig is, but I have a 2011 Sportsmen Classic 19BH. There is a fuse on the hitch. It is a 30amp fuse that comes right off the battery. If that is blown, you will get nothing in the camper without shore power hooked up. I had it blow on my camper 4-5 years ago. Not sure why. The replacement was only a couple dollars and you can probably get them at an auto parts store or if not, any camper dealer or supply store will have them.
This view is taken from the front of the camper looking back towards the camper.
I am going to be "that guy" and make a correction here. What is pictured isn't a fuse, it's a (when working) self resetting circuit breaker, they do make a version that has to be reset manually, there is a small button on the side that has to be pushed back in to reset the breaker. With all that being said, if your coach has a battery disconnect switch, is it on? If it is on, is it allowing voltage thru? They have been known to fail.
2018 Durango 318RLT '20 Ford Lariat F350 4X4 Former RVIA Master Tech, ASE Master HD Truck Tech.