Why do you think its a problem with the socket? If your cart uses lead batterys like they usually do, they go bad in about 4 years. Check the voltage on the battery. You might have multiple 6v or 12 volt batterys and you should check the voltage on each of them. If a 12v battery shows voltage under 12v, its trash.
I had the same problem. Had to take it to the shop since it was under warranty. It turned out to be a loose connection to the screen. They had to replace pretty much everything on the phone in the process. If I were to do it myself I'd take off the screen and re-attach the ribbon cable.