Sorry I can't provide any help. I'm just impressed and want to thank you for sharing your experience. It appears you are the first one showing how to open up the dashboard of F25.
I have the same 6.5" screen as yours. I also want to open the dashboard up but just to install an iPhone snap-in adapter in front of the screen. IPhone's navigation is good enough for me. I just want to control my Rdio app for music. The iDrive only controls Apple's music app.
So if I have a USB cable and a USB plug, is there a place in the dash that I can hook up USB plug into the system?