== Fixed by attaching the wires directly to the PCB ==
I had this same problem after 5 years. It was impossible to source a replacement PCB and wire as all the Panasonic spare parts places are out of the TNPA6831 board.
[image|3390268]
The PCB itself was fine, but the header and wire connection were melted. I was able to get it fixed by having a mobile phone repair store directly attach the wires to the PCB. It's 2mm spacing between the wires, so it was beyond my soldering abilities.