Samsung Note 3, TMobile, KitKat, 128G SD card, 3yrs old. Operation has been normal. Today I was streaming music from the phone to my car stereo via bluetooth. Battery was low so I plugged it into the USB port for charging. The display showed "connected as a media device" and the phone indicated charging. I unplugged it for a bit, then plugged it back in for more charge. This time the display showed only a USB symbol, and the phone did not indicate charging. Black screen, and after that, attempts to reboot the phone result only in the TMobile splash screen. Can't get any further, can't shut it off, no response to inputs. I've removed/replaced/charged the battery but makes no difference. The phone seems a little warm. Any ideas?