First, Welcome to JOF. You'll find lots of help here.
Sounds like it used to work on gas, how about electric when plugged into campground power? Have you checked fuses? Perhaps most important, still under warranty?
I'm guessing yours is an Atwood WH - there's a small 2amp fuse on the circuit board that you see when opening the outside panel that may be the problem.
2014 Eagle Premier 331RETS
2016 Silverado 3500 DuraMax/Allison
1975 Corvette & a couple ATV's