* Check your battery
voltage. Is the battery
going dead? Low voltage can cause all sorts of strange behavior.
* Are other pieces of equipment
turned on? Especially anything that draws a heavy load? Big load transients can cause equipment
resets, and poor connections can make this much worse.
* Is the engine
running? A bad regulator
(or connections) can create spikes, again causing squirrely behavior.
* Check your connections.
* The radio may just be failing, probably due to humidity / salt
. Or gremlins. You can't fix gremlin-caused damage, you have to replace the equipment.
*** "All buttons are inoperable
" *** OK, this is likely a radio failure. Still, it can't hurt to try looking at the other possibilities. If you have clean 12V power and good connections, it's time to replace the radio.