Hi, my S4 charging symbol blinked 2 or 3 times and then it quit charging while it was plugged into the wall. It still works through USB, but if I shut the phone off and plug the charger in the socket the phone vibrates every few seconds with no notification of charging, if the phone is on and I plug the charger in nothing happens. Anyone have this problem? I have 2 chargers and switched them all around and no luck. Thanks in advance for any help.