I have had trouble with our 169 boot release. I removed it and it was a buildup of very fine dust and dirt where its hinge pivot fitted. It was so slight I woulnt have believed it would cause the problem. Its been fine since cleaned. Door handles are fiddly things but other cars Ive done have been straight forward. The worst bit is usually repacing the damp seal behind the door card. Get some strip mastic from a caravan dealers to refix it. it works and saves time and distress. Replace the plastic sheet if its ripped again not worth mucking it up for a fmall outlay.