@XbladeX From earlier experience with a problem like that:
try these steps:
Activate the SSH service in DSM (if not active)
Connect to your NAS with an SSH client (e.g. putty) (or from Win 10, open a cmd window, run : ssh admin@my.nas.ip (replace with the actual IP)
Enter your credentials (user: admin)
Change folder to root (cd /)
Delete the xpenoboot folder (sudo rm -r .xpenoboot)
If the SSH service keeps stopping, you have to be quick.