Key to the roof opening or closing is the stage where the rear portion of the roof flips forward (towards the front of the car). If this doesn't get to a point just beyond vertical (looking sideways vertical would be 12 'o' clock, so the rear portion should go to one 'o' clock) the tonneau won't be able to open. If the rear portion is getting beyond vertical but the tonneau isn't opening at all then this will be down to either a failed motor, a broken bowden wire (the cable that opens the tonneau) or an electrical fault at one of the sensors. This explains the principle behind the roof opening procedure and some common fixes...

http://www.bimmerforums.co.uk/forum/...p-roof-t67212/