Kevin, I had the same situation with a 2016 Thor Miramar I had. I believe your problem is with the furnace circuit board outside of your motorhome, it is a very common problem. When the circuit board gets wet, it does not lite the furnace. What I did was remove the outside panel where the furnace exhaust is. The circuit board would be right in front of you. I blew compressed air on it until I could get it dry and then it would work, you can also use a hairdryer, it was only a temporary fix. They make some sort of relocation unit that has to be put in by a dealer, good luck with that. What I eventually did was remove the board from its base and screw it into the side wall of the furnace housing or camper wall being careful to keep it away from anything that had heat. Make sure you turn the button located right at the circuit board to the off position to avoid any shock. Be sure to make sure there is no corrosion on the circuit board, if there is, I used alcohol, sparingly to clean it, letting it dry.
I screwed it into the wall, so no moisture could get on it from any kind of water dripping in or around the gasket. You can research this and I believe you will come up with the same findings. Good luck.
