You didn't mention a year or model, so this may be way off, but it sounds like all you've lost is 12V power. Two things I would check:
1) If you have an electrical control center, check the 12V breaker. It's usually a very small black button on a white circuit breaker at the lower right of the ECC when looking at it.
2). Assuming you have multiple coach batteries, try bypassing the one closest to the coach. If it has dead cells, etc., it could be keeping power from reaching the coach.
Hope this helps. Good luck.
2015 Legacy SR340 360RB
2014 Jeep Wrangler Unlimited Toad
Gigi, Poppy and Sadie Lady...On the road, but not full time!