AUX Stopped Working After Head Unit Install

[flip]

Hello all, this is my first post here and I'm a bit new to the X5 world but definitely not new to BMW's...

To try to make an extremely long story short, we purchased an X5 without NAV and the dealership installed an aftermarket NAV system. Prior to the install, the AUX input (1/8th inch headphone jack) worked perfectly fine. Afterwards, it did not and there was no sound out of the aftermarket unit.

After some digging, I found that the aftermarket unit uses the AUX input to output its sound so this is why there is no sound from the unit.

Now, why the AUX doesn't work at all, that is the problem. I disassembled the center console and armrest enough to find that the stock plug was still plugged into the aux port/usb and I see an optical cable plugged into a little box in the arm rest as well.

Any ideas on what else could make the AUX stop working? The manufacturer of the unit has been trying to assist me via email and suggested that the optical plug that goes to the back of the unit from the AUX might have accidentally been unplugged. Does anyone have diagrams of the stereo system, or know what all is required for the stock AUX system to work?

When I plug something into the AUX plug and go to the AUX input on the car's stock system, the volume for that input is all the way down and I don't have the ability to turn it up at all...

Thanks in advance for any help!
-Philip