My i-phone is about 4 months old. it says it is charging but does not charge. This all started within the last week.Once it charged to 100, sometimes to 20 or 30%. Today it is not charging at all. I restored from my computer two days ago. Today i reset the i-phone. says it is charging; battery has dropped from 9 to 7% I have tried 4 different apple cables; two wall chargers and two into computer usb. Any suggestions?