Hi, I like your post about the mirror. I have E90 as well, just got it a few weeks ago. When I was cleaning the glass, the two halves came apart and fell out (the ones around the mirror base) and I saw one small circuit board just hanging there. Could not figure where it attaches, seems like it has sticky residue so I am assuming it was attached to the glass. I included the picture. Do you remember where it was on your car? Thanks.