Using the search box at the top of the page with the Google logo, this is the list of threads that is generated:
https://www.google.com/search?num=10....0.xPBpdRqq2_g
You didn't mention RV make, model, or thermostat make and model. If you use Google to search for a manual for your thermostat, perhaps that would be a first step. Many folks with digital thermostats find they have to shut off all house 12v power or pull the fuse for the thermostat for a few minutes to reset it. Just a few things to try...Good luck.