(Don't know how to edit my previous post) I already found a fix (and wanted to share it to help others with the same issue).
I tried to manipulate the Web Assistant to think the device was an different model and succeeded only partially. Spend way too much time trying to solve it this way. This is how I recovered my 1010+ (With 1511+ DSM 6.2)
I've used telnet (telnet <ip>) to access the server using root and the generated password as mentioned here. Busybox allows you to make all the changes mentioned above. (modify /etc.defaults/synoinfo.conf and /mnt/boot/boot/grub/grub.conf etc to fix the issue)
Reboot the NAS and then use the Synology Web Assistent reinstall/migrate data.