Using SD to boot after moving system to USB via openhabian-config


I just ran into that trouble with the lates Upgrade and now my Server/Touchdisplay Raspi3 always freezes the screen a minute after autostart of the GUI. I obviously have problems with my static IP-Adress, too.

As I just recently moved my system to USB via openhabian-config, I would like to simply switch back to my SD-card. But trying to boot from there gives me errors too, as there are obviously changes on that card to avoid booting from there. During boot-process I see that the system is waiting for the USB device and then exits to a Shell.

What will I have to do, to reuse this SD-card? I remember, that I read something about it earlier, that seemed to be quite simple, by just editing one file on the card. But I cannot find it again.