So my PCB managed to supply power the wrong way round to the 6-way header on the BDM cable.
PC and debugger IDE still pick up the BDM on the USB side - blue LED illuminates, but when I connect voltage to my target board pins there seems to be a shot. (Orange LED does not turn on).
If i supply 3V directly via PSU to the GND and VCC pins, the yellow light does come on but it draws quite a bit of current. I noticed some protection zeners against higher voltage but I dont think there was anything for reverse bias.
Any idea what I could have popped?