This has happened twice.
I reconnect the 817 in the mobile-mount position in my car after an activation. I check it is receiving a voltage >12 (which indicates it is running off the car battery as intended) and set 2m to the rear antenna connector (it is usually set to the front terminal for an activation). I then turn the 817 off while I start my engine. I turn the 817 on again, but find that none of the buttons (band/mode change, F button, V/M etc) work. Only the rotary controls and the on/off button works. No procedure (turning off and on again, disconnecting and reconnecting to car battery etc) rectifies the problem.
Turning the rig off and leaving it off for an hour or two, then turning back on, and everything works normally again.
The first time it happened, I wondered if cold/damp had got into the rig and it needed to “dry out”. But the the second time, it was actually after running the rig in a scout hut for JOTA! And on both occasions, the buttons all worked when I set antenna connectors etc after reinstalling into the car. They just then didn’t after starting the engine! (But did a couple of hours later).
Confused. Any ideas?