ReadyNAS Pro 6 boot failure, migrate disks to new RN526X00

StephenB and Sandshark  Thanks for both your suggestions.  Yes, I had installed RAIDar on my Mac and it was only reporting "Status: System starting up...".  After exhausting other debugging attempts (including verifying power supply voltages because I did have to replace that a couple years ago), I pulled the 2 drives from a ReadyNAS Duo which is no longer in service.  The ailing ReadyNAS Pro 6 detected those two drives and booted, although it does not mount the volumes presumably because of the NAS differences.   I then proceeded to try one of the drives in each of the 6 slots-- it would boot the system in each of the slots, but still failing the filesystem check as I would expect. 

So this raises questions about the original 6 drives in the system.  Could one of them alone hold up the boot process like this?  Any suggestions from here would be greatly appreciated.

By the way, I had an RN628X on order but my distributor is claiming these were discontinued on June 1 and cancelled my order.  I was surprised since they are still shown as an active product on the Netgear site.  I'm still wanting to replace with Netgear in hopes of transferring data.

Thanks much!

Mike