this how i solved the problem with the error restore processes NOT the FACTORY DEFAULT
Take the hard drive with the OS that means the first one from the bottom, take it out and plug it in the an external computer. When the partitions pop up look for the "sys" partition. It should have something around 20 gb partition. That has the OS on it and the "DATA" is just what data your sharing with the rest of the hard drives.
DO not format the DATA only the SYS partition.
The Failure is caused by failing to format that partition. So just manually do it your self and then just pop back in to the drive bay and try the method all over again.
it should work.