Rear Dvd entertainment screen not working

[Bigchop04]

We have a 2017 escalade and the 2nd row screen will not turn on.  Stealership already charged me $120 to “diagnose” the issue when all I asked was if it was still under warranty.   I’m a few thousand miles out of warranty.  Anyways I’ve replaced the ribbon cable to no avail.   I even took the 3rd row down and stole the cable from it to try OEM cable and still didn’t work.  The 3rd row player is working with aftermarket cable now.  What else on these players can go bad?   I fiddled with the screen on off switch and it didn’t change the result either.  Lights on sides and front both come on when plugged in just no screen whatsoever.