For users with similar problem: FIX
1. deinstall ML from camera -> process via Canon firmware-update, waiting, ML removes itself, resets bootflag;
2. change nothing - start the camera, have a look if everything works as it should. Then:
3. start firmware update again, ML installs again.
fine. As it seems this was a camera-internal problem or a problem with the sd-card. I changed the card after steps 1-3 to a new one. Perhaps it has been damaged by age or some other influence (reading out outside the camera or other)
So everything is fine.
1. deinstall ML from camera -> process via Canon firmware-update, waiting, ML removes itself, resets bootflag;
2. change nothing - start the camera, have a look if everything works as it should. Then:
3. start firmware update again, ML installs again.
fine. As it seems this was a camera-internal problem or a problem with the sd-card. I changed the card after steps 1-3 to a new one. Perhaps it has been damaged by age or some other influence (reading out outside the camera or other)
So everything is fine.