The original story (from this link):

[someone did] flip the circuit breakers without my knowledge.  Now my Readynas Ultra 4 Plus is not functioning properly.  … So thought I do some troubleshooting.  I tried to update the firmware [it won’t flash].  … then … i try disabling CIFS and re-enabling.  Now it won’t re-enable at all. Raidar reports everything is healthy.  The ReadyNas Admin page also seems like everything is okay,  However I just can’t access the data.  … So what are my options?

1) Can I go and get 4 blank drives.. Restore to factory?  Then try to put my old drives back in?

2) Do i have to get something like ReClaime or R-Studio to recover my data?

b)  If so is there any good step by step guide on how to do it?

I wish there was a way to do restore the OS to factory without losing the data.  I am sure the Raid Partition is intact, it’s just the OS is malfunctioning. …

What can we learn from this?

1. Even in 2015, sudden power failure can kill your NAS. NASes are considered fault-tolerant, just not with all types and kinds of failures.
2. Firmware flash on a broken NAS is unlikely to work. In other cases, it may actually make things worse, so I would advise against even trying.

Does he actually have to use something like Home NAS Recovery, ReclaiMe, or R-Studio? In all probability, yes. There is a good step-by-step guide, here. Restore the unit to factory conditions with 4 blank disks, and then swap disks for ones with data will not work. The configuration is stored on disks, and factory config after reset will only apply to the new 4 disks. Once original disks are in, the fault is back in.