Cynthia plugged her iPhone into her laptop and when she did, it shut down her Mac. She was told that it could do that with a third party USB cable. Leo says it's not likely a compatibility issue, but it could be a short in the cable. What about a message that says "battery needs service?" Leo says that's more likely the issue as batteries do stop charging after about 500 recharge cycles. So Leo believes the shut down was coincidental. Getting a new battery should solve that problem.