I just tried it again and it's working!
There a only a few things that are not perfect.
I still need to manually turn off the intel inject, otherwise it won't boot and only produce an ugly graphics bug.
The sound is not working and I have no idea how to turn off the bluetooth.
Thank you very much for your help and the guide!
/edit:
okay, I could switch off bluetooth in bios. This works for me. But I still have a high pitched clicking noise. I've read that it may come from the bluetooth, but it looks like turning it off did not fix the problem.