I had a similar issue with mine. It turned out to be the chargers themselves. The plug part that goes into the phone was damaged on both the car and home charger. It would only work if it held the wire upwards til the tiny red light lit up. Another issue I had was that the phone was plugged in on the charger for hours and it wouldn't pass the 20% level. The phone was off too! I took out the battery; waited for about a minute; put it back in and it charged as normal.
GOOD LUCK!