Magellan Roadmate 760 GPS Receiver "power unit sound hit bump" Questions

...unit to turn back on. Put the screws back in, and it is good for a day, maybe a week, then won;t power up. Take the back off, move the board, and it will work again for a while. Gotta be something ...

...unit itself never uses power I doubt that this is the issue. Do you have any idea where to begin diagnosing? Can one bad speaker connection cause lose of sound to all speakers? Yes, one bad speaker ...