5V sensor/ground issues.

Hobbyist here attempting to sort an issue and potentially learn something along the way......at least before I admit defeat and send it to the shop.

FD RX7 w/Haltech Elite 2500, professionally built club level loom.

Having completed a 20 min track session, upon returning to the pits engine protection tripped and I noticed my IAT/CTS and oil temp readings at max, ECU temp high, along with TPS and some other DTC's relating to the 5V sensor circuit (sensor reference voltage ratio, sensor reference voltage VAN 5V ref)

I've gone through and disconnected all the sensors/AVI's to eliminate a short to ground at the component end, with no joy. The 5V supply pin (A9) on the ECU is supplying 5.12v, but when connected I see 0.17v +/-. There's no obvious signs of heat damage to any wiring, although the timing of the failure leads me down this path.

Before I go and dismantle this loom, and/or send the ECU away to be checked, is there any way to further narrow down what may have caused this type of issue?

FWIW - managed to find a melted turbo speed harness before ripping too much apart - great outcome!