This is a bit perplexing!
Often the cable is the issue, rarely have I’ve seen the board fail, I’ve had to replace a few due to liquid damage. The cable issues tend to be at the connector interface. The pins bent or not making contact or again liquid damage.
I’m suspecting the logic board connector is damaged or again liquid damage within the area.
At this point you’ll need to grab a set of schematics and board view drawings and carefully trace the WiFI lines between the logic board and AirPort board.