I did have the same problem, here’s what I did. (1) used original cable and charger (2) got the amber power light to flash (3) did the “press Play/Pause for 15s; disconnect power” reset. (4) turned unit back on, and immediately did a factory reset by holding aux & - buttons together (5) paired my Bluetooth device again (6) it has been playing for half an hour now, but cannot turn off the unit or switch sources. It is basically frozen in the ON/Playing state. I’ll need to go through the above steps to use it every time.
What did you use to monitor temperatures before and after, accurately?