Just my 2 cents...
If you get the error "unknown keyword" after the "unset all" command in CLI.
i had the problem that i had console rights, but not root level access.. you can go to Admin Menu and see for the root user you need root access..
With my console user i had only "read-write" rights and these are not sufficent to get the SSG back to factory settings.
Regards,
Frank