No Volume Found after HDD replacement

Hi --

I have a ReadyNAS Ultra 4, configured with X-RAID. We had a disk failure, and replaced the bad disk with a like HD. The system began to re-sync, and after a number of hours (4x2T drives...), we received an error in the logs stating that a checksum had failed. Now, when we boot the device, the volumes page gives a dialog saying "No volumes found. Some functionality will not be available" - Paraphrasing since since I don't have the exact text in front of me. The GUI shows no volume information at all, but it has retained all my other configuration (networks/alerts).

RAIDar shows the NAS on my network, and I can see that all four disks are green, but it as well doesn't show any volume information.

I've tried re-installing the firmware hoping that the process would re-find the volume, but that did not work. I haven't attempted a usb recovery yet, figuring I'd post here to get some more pointed help.

I do have another very similar ReadyNAS (Pro 4). Is it possible to compare the config backups, and see where something is missing, to try and re-create the appropriate conf files? Just a thought - not sure if it's possible?

Thanks in advance,
Mark