Move to new NAS

Ok, bear with me here and I'll try to keep this as short as I can while still providing the background and events that led to where I'm at.

I have a primary RN and a backup RN. A couple months back I noted the backup RN was unresponsive and reboots didn't help. With help from the forum and Stephen's in particular later, I was able to get the firmware refreshed and diagnose three disks with rising errors. It would run but eventually hang so I couldn't use it or copy anything off of it and I didn't have the money to purchase three new disks. I also replaced the PS on this NAS because it seemed like an easy thing to refresh and cross off the trouble list. I eventually just yanked the three disks and rebuilt it fresh but hadn't yet backed up anything from the primary. The other day a friend gave me three drives matching the size of those in this backup RN and I added them but had not yet started a backup. Famous stupid decision...

Because in the meantime for several months I had noted alerts on the primary RN that one of the disks has 51 errors. Again, lack of money for a replacement 8tb drive had me biting my nails. Finally I was able to purchase a replacement drive and thought I would also refresh the PS. After replacing the PS that system won't power on at all, not even with another known-working PS on the bench. No lights, no nothing just totally unresponsive. This needs more investigation but its not looking good.

So, I pulled the drives out of the backup RN and put the primary drives in it. It booted and seemed ok so I swapped the bad disk with the new one and in started to resync. The next day I noted it was hung at 75% or so. Sometimes it would boot sometimes it wouldn't. Sometimes with the new disk, sometimes not. I tried putting the old errored disk in and it started resyncing that, then failed a 5%, hung. Realizing the firmware on the disks is older than the firmware on the backup RN, I eventually was able to get to the boot menu and reinstall the OS. It failed a couple times and hung a couple times and often I couldn't get to the boot menu, it just stuck on the display showing Readynas. But eventually it did it all like it should and came up seemingly ok. But it still hangs when resyncing. And in fact if I try to pull data from it via backup software on PC on the network, it hangs within 5-15 minutes. I'm doing this with neither the bad disk or replacement in place, so it's flashing degraded all the time.

Sorry this was long winded, but worthwhile I think for you to know the sad saga.

I've done a bit of a google for replacement Netgear boxes and agree they are rare and unreasonably priced. The idea of finding a chassis to take the disks and use Linux to mount them if only to be able to backup is a great one but I would need some serious assistance with that. I have a Linux Mint workstation but would an external multi disk chassis work, even a USB one? I'm not sure what to look for. That software mentioned is also affordable but not sure if that suggestion is part of the Linux idea or an alternate.

Sorry to ramble. I'm stressed. Any assistance is greatly appreciated.

Robert