Repair Date: 02/02/2013
A customer brought his phone to us after a DIY screen repair. He had pulled the battery connector off the main logic board while disconnecting the battery. A PCB track had been lifted and a pad pulled off. The battery on the iPhone 4 and 4S have four connections to the logic board, 2 are power and 2 are data lines used to read information from the battery. One tale tale sign that the battery connector has been damaged is the phone either restarts every 1 minute or does not charge correctly. The phone cant read the temperature of the battery and hence cant control the charging current correctly.
The solution, is to remove the old socket, replace the damaged pads or tracks and reflow a new socket back onto the board.