원문 게시자: mayer ,
Your machine does not have a PRAM battery. It uses a small capacitor on the logic board that should last for 10-20 seconds while changing the main battery. Your main 47Wh Lithium Ion may need to be replaced. If it has a charge, reset the PRAM by starting up and holding down the Command - Option - P & R keys and wait till you hear it tone three times.