Had the same problem. Turned out my charger"cord" was kinked at one or both ends - and it was NOT noticable at all.
Keep in mind it was ONLY the charger"cord"( NOT the USB/Plug in square piece that you connect the cord into and then plug into wall!)
Confirmed it at TMobile store, and saved money by not having to buy the USB/PLUG IN Piece, just a new cord.
$30 total to fix it!
Hope this is helpful.