This might save you a bit of dosh...
It's a wee story... launched the boat, switched on the instruments and sounder is dead - bugr, anyway, went off and had a good day's boating. So, got around to checking the sounder today, a Garmin 298, power..check, a good ground...check, hardwired directly to the unit's pins...dead. Had a quick scan of eBay...nothing. Maybe a reset needed...nope. Phoned Garmin...no longer supported or repaired and nothing the same size to fill the hole - bugr again. Nothing to lose, lets pull it apart and a have a look see..nothing untoward in there so gave the circuit connectors a wriggle and connected power just in case...blow me, it fired up as good as ever!! Gave them another wriggling for good measure and reassembled it and reinstalled it.- all's good. It's not the first time I've had a piece of electronics come back to life after an internal connector check.
So, don't throw it away without a seriously good check over.....