On my '03 Bounder there is a power distribution relay, mounted on the right side of radiator frame and accessed under the passenger side wheel well,. This relay supplies battery power to the dash and everything needed to crank the engine. Locate the relay, disconnect the battery, and burnish the contacts. I've been there and paid an "RV tech" $500.00 to find said relay and clean the contacts. Symptoms are exactly as you stated. Perhaps you can have the guy coming check this out, prior to wasting a bunch of chargeable ($) time. Good luck, I hope this helps.