Behind the outside cover you will likely see a black plastic cover which is over the circuit board. May find that the screw at the top will remove it. Unplug the 120 volts to the trailer and take the negative lead off the battery and you will not have to worry about electricity. Remove the cover and see if the small glass fuse under it is blown. If so, your electric heater is likely bad and will need replacement, but you could try replacing the fuse to see how long it lasts. The electric heater will be in the stack over on the right side (from the outside). The stack (maybe not the correct name--Doug will correct all errors on line) has the gas flame at the bottom and the electric heater on up in it. There may also be an over-heat reset button on the stack. You may have to remove a cover to get to it. I think that it will kick out both gas and electric so a blown fuse or bad electric heater is more likely.
I would google for RV fridge repair in your area. Around IN we have small specialty shops that only work on RV fridges, and I'll bet they are better than the typical camping service department--which is not to disparage the few really good camping store service departments.
Since it has been brought up, IMO you'll die richer if you never buy a RV extended warranty. The extended warranty companies in the RV business have a poor reputation.
