Better to post good quality picture to be able to tell. But you can look at it yourself can see any physical outside damage if present at all. This doesn't need any expertise in my opinion.
You shouldnot have never taken it for warranty repair when the cover was missing. It gives them a clue. Just get a cover and then you may want to give a try at another dealership. It is quite expensive part, I have been using it since past 4 years now and so far no problem. Good luck.
650i F12 - HUD, 6WA, SLI, Logic 7, Dynamic and Adaptive Drive, Comfort Access, Soft-close, top-view,
Previous X5 40d M Sports and 535d LCI