OBD port and rear tail lights not working

Purchased this car used. The OBD2 port will not power on, does not work at all. The non OEM radio also will not give sound, powers on fine.
Tail lights do not come on. Brake lights work.

This is what I have tried:
-Two different obd readers.
-changing fuses.
-new battery.
-has new, spark plugs, oil, oil pressure sender, oil filter, coolant flush, belts and tensioners.

Every thing else works and runs fine. So I am at a loss as to what this could be.

It is at the dealer right now and they want over $600.00 to trace the wiring harness back to the end and try and find the problem.

Is there anything else I could try before forking over this kind of money? The dealer was my last ditch effort, but that is so much money!

Thank you for any help you can offer.