I fixed my old Mavic Pro. Just needed to work the grains of sand out of the motor. I basically needed to hold it upside down and force it to turn and the grains fell out. It still sounded a bit crunchy in there when I turned it so I did some tapping, vacuuming and more forced turning until the crunchiness was gone. It has worked just fine since.

My Mavic Pro also has a motor suddenly refusing to turn. No crash, no broken off tabs, just not turning, as if locked somehow. Any other ideas?

Using another Thunderbolt cable attached to the additional port on the display instead of using the built in cable solved the problem for me. At least I now know that it is the display cable and not something with my Macbook. Now I will get a replacement cable for the display. Can anyone tell me if it can be opened without suction cups, or are they necessary? Thanks.