Hold the new rotor up to verify you don't need to remove the big nut--I'm pretty certain you don't.I removed the caliper and torx screw but the rotor won't budge. Do I need to remove the 36mm, 12 point nut?
Caliper ALWAYS comes off before the rotor.It's been a while since I did such mechanical work (like 40 years or so), but I wouldn't think the rotors would be held on by the caliper. Might want to search the web for how disc brake rotors are removed since I would think the MB would be the same as others. I have a VAGUE recollection of having to remove a nut, but I can't say for sure. I also wouldn't think the hand brake would be affecting the rotor removal either.
Hopefully someone else will have the answer. Maybe post a message to DansSLK section. Sounds like something Dan would easily know.