ReadyNAS Ultra 4 - cannot get it boot, have tried almost everything

I've got a ReadyNAS Ultra4 (RND4000) that used to work.  Won't boot now after an attempt to factory reset.  To date I have tried:

1. Factory Restore

2. OS Reinstall

3. USB Recovery (3 different sized and type USB drives) - none of them would boot it [This was with the 4.x files because that's the firmware that it had on it]

4. Remove, test, and wipe every disk (hard drive diagnostics all passed, disks were wiped using "clean" in diskpart)

I always end up either with just a flashing cursor on the front display, or it just says "booting" forever (I've left it overnight, it doesn't boot at all ever).

When I factory reset/os reinstall it will show up briefly in RaidAR, allows me to select a disk configuration, but at some point it just gets stuck at "booting" again and never finishes.  I'm assuming that something is corrupted on the firmware, but I have no real idea how to fix this at this point.  I sent an email into the black hole of Netgear support several days ago and heard nothing.

Is there anything else within reason that I can try?  Anyone that knows how I can get help for this?

Thanks!