1999 GMC 2500 6 liter engine 4WD

Owner contacted us saying no one in his town could figure out why this pickup
would not start so he had to trailer it 200 miles to us
Owner stated they had put a code reader on and reported not DTCs at all.
They thought it was a bad fuel pump relay but not the problem

Engine would not start at all, found fuel rail pressure was fine
Hooked up OBD-II scanner which could not connect to PCM at all

Started checking wiring out and found nothing wrong with them

Check fuses to find ECM1 fuse blown. Replaced fuse and that blew

Yanked out PCM and took it cover off and instantly had that burned electronics smell
As shown below found burned motherboard on both sides
Cut the 2 80 pin connectors off a old PCM to connect those to wiring harness 80
pin connectors and rang out all wires and found nothing wrong with wiring or any
defect of sensors, etc

Flashed another PCM, tuned it and all is well now
In 20 years of tuning never seen a PCM on it's own burn so anything is possible
when having a engine problem !