Radio and Extension Box Malfunction

Hello friends,

Sorry to make another post of this issue, but I've tried everything suggested here with no avail.
I bought a 2012 with the JBL radio that had the symptoms of the extension box malfunction: Apps button not working, Steering Wheel mode button not working, Bluetooth not working under setup, etc..

This is what I've tried so far:
1- I've tried replacing the extension cable first with a brand new one purchased from the dealership. Didn't fix it.
2- Replaced just the extension box from one purchased on ebay. Didn't fix it but it could have been a defective box.
3- Purchased a Radio/Extension box combo from ebay and it worked ONCE, I was able to pair my phone and the apps button was working fine. When I turned on the car again I was back with the same initial issue.

I tried entering the secret menu, the EXT box says OK. The EXT BOX under diagnostics does not work.

What else could be wrong? Why did the last replacement worked for 1 time only?

Thank you so much for your help.