[Pursya]

Do you know an auto electrician?
Because that would be my first port of call, considering the “drop out” situation.
Vibration, or heat can cause disruption in the electrical supply. As for the buttons, that’s a common problem for all push button devices. You need to google the issue. Should find that pulling the keypad apart and giving it a good clean can solve that issue.
Unfortunately, the work/not work appears to be a random event situation. The hardest ones to track down.
I’m shooting in the dark here, like you I’ve no actual idea/proof that my thoughts are the issue.