They at one time had an Xfan upgrade kit for the Xdrive. There was a competently different wiring set up between the Xdrive with Xfan upgrade and the Xdrive+Xfan kits. I had troubles with my xdrive+xfan kit and ended up sending in just the top piece and the xdrive for replacement. They sent me bad out a Xdrive kit and I ended up having to build my own wiring adapter to make it work.
The Xdrive when you press the button on the top it is intended to switch between and internal disc drive and an external disc drive. With the Xdrive Plus Xfan kit they set it to so that pushing the button just turns the xfan on and off while staying lite up.
I dont know what to tell you other then if you cant find the Xfan upgrade for previous Xdrive owners then your better off just getting a complete new kit.