Thanks for the write-up. I've done this style of hard-wire to about a dozen BMW's now, but always have to do a search when I buy a new car so that I know which wire to tap into!
BTW, the fingers through the front of the headliner in brilliant! Much easier than the way I did it with my 335i........that was very aggravating!
If anyone gets the SOS error message
it's because you haven't plugged the wiring harness back into the panel yet!
Ask me how I know.......