I would just mount the drives and then use backupmenu to access the / filesystem, since you dont have clean backups, and delete the two files you made.
/etc/udev/rules.d/98-bnep0.rules
/etc/udev/bluenet.sh
Then try to reboot.
If that doesn't fix the problem then it seems that other files have been edited or deleted.
If the above doesn't work I hope you have clean backups.
If deleting the two files doesn't work then it is something other than the BT tethering that has gone wrong.