Thanks for the writeup, although I'm sorry to see that this problem is affecting S65 as well as S85s. I did a teardown on one of these yesterday over at M5Board
I am trying to find a way for people to repair these themselves, but haven't nailed down all the failure modes yet.
If anyone uses this DIY to themselves and is willing to donate their dead actuator to the project, I think both communities can benefit from it.
The actuators for the M3 and M5 look identical although they do not share part numbers. I suspect this has to do with different programming for the CAN bus signals passed to them from the DME, but I don't have an M3 actuator to compare physically.
If anyone wants to get involved, PM me here or over on M5Board.