*edit* fix that ski hole door.
In my experience with BMW's, it was most common for the wires in the rubber tube between the body and boodlid to break due to the opening and closing action of the boot. and the only way to fix it was by drilling holes in the bootlid to get it open again.
I'd be checking fuses and relays tho. just take em all out one by one - pull, check, replace. the worst thing you'll do is lose the stations on your radio.