Had that same problem with my old 2003 Horizon. Couldn't get the storage bay radio to work, one day looked at it hard, found that the previous owner had unplugged the power cable.
I hooked it back up, and found that it would turn itself on randomly. Seems to me at the time, I figured out the radio was resetting itself when the RV was powered off. I think (years ago) that I routed 12v power from a compartment light fixture, and the problem was solved.
2010 Journey 39n - 2017 Jeep Cherokee Trailhawk - in our 9th year living aboard, now in Texas for the winter season