My iPhone 5s shuts down at approximately 38%, or sometimes when I'm using Camera+ or talking to someone on the phone. Just BAM. Shutdown. No warning. When I plug in the charger, the battery life will reflect the un"dead" rate of 38% (or number other than "0"). Does RESTORE TO FACTORY SETTINGS fix this issue? I'd like to save $79 for a new battery if possible. My phone's serial number is outside the 5-month battery issue timeframe for Apple battery replacement.