You can unplug the charger and clean the connector and if that does not work you can check to see if there is corrosion on the charger adapter or if it is loose in the phone. If this is the cause you may be in the market for a new charger. If this is not the case it could be a phone/battery error and this would require you to send it in so you can get a new device or we can fix the tiny electrical components that makes your device charge!