Replaced head unit, fixed one problem but caused more

[M-PWR]

I'll try to keep this short.
Basically I bought an 12/04 e87 with a few problems (at an amazing price) a few weeks ago and have been restoring it myself.
One of the issues that I was faced with was a head unit that turned on and off whenever it felt like it and when it DID turn on the LCD was all messed up.
So it was a Professional unit with NO USB option

^Photo of original head unit in my car
So then I went and got second hand head unit removed from 08 e87.
This unit was a Professional unit WITH USB in the original car


^photo of the new head unit in my car ( I did a full interior facelift conversion)
The original problem of the head unit with mind of its own is now fixed and the screen issue was obviously resolved as well.

However now I have 2 new issues.
1. Both cars obviously had the AUX input under the armrest but as shown in the photo above, when I plug a 3.5mm plug into the jack I still don't get an AUX option in the HU. I have done a few hours of research, I have disconnected my battery etc, I'm starting to think that it might be a coding issue perhaps?

2. Not really an issue but more of retrofitting idea that I am a bit confused about. Looking at the wiring diagrams for the cars stereo system on realoem. Keep in mind that I performed an interior swap and currently have a USB port under the arm rest but there are no cables connected to it and it is not functional however.... It seems like all I need to have USB running in this car (which didn't come with USB originally but now has the option in the menu) is the cable from the back of the head unit to the port under the armrest? Am I correct about this? is it simply a connection from the back of the head unit to the port or is there another module involved? Where is this module located on the donor car?
So I basically currently have: head unit with USB option in menu, USB port under the armrest with no cables... and access to a car that came with the factory USB option

[JimD]

I don't see why you shouldn't try connecting the usb with a cable to the head unit. Seems like it will either work or it won't.

My radio only will show an aux input when I have a device plugged into the port. Do you have something plugged into the aux port? If the answer is yes and still no aux on the radio then are you sure the aux cable inside the console going from the port to the radio is plugged in at both ends?

Jim

[M-PWR]

Originally Posted by JimD

I don't see why you shouldn't try connecting the usb with a cable to the head unit. Seems like it will either work or it won't.

My radio only will show an aux input when I have a device plugged into the port. Do you have something plugged into the aux port? If the answer is yes and still no aux on the radio then are you sure the aux cable inside the console going from the port to the radio is plugged in at both ends?

Jim

Yes, cable is plugged in at both ends and I have my iphone hooked to the port...