. . . if you haven't turned off all battery power, try that.
I had flipped the circuit breakers earlier, to no effect, but with nothing to lose I tried Pickerel Cove's suggestion and flipped the Battery Disconnect switch off and then back. Surprise - the Control Panel lights came on and responded to my switching to AC, although I'm not sure I got any cooling, since I didn't hear anything running, even though I usually don't notice refrig sounds. But within two minutes all the Control Panel lights were out again & didn't respond further.
