(not) Booting after disk failure

Please try to remove disk 1 and power on ReadyNAS, then insert disk 1,
Replace a disk when the unit power off, the system will not power on successfully if the disk has different partitions from ReadyNAS, the disign is for protecting data on the disk, we worry user insert a wrong disk and he don't want to format data on the disk.

Frying pan to fire... Now I just get stuck at the "Booting..." phase after a couple "Checking FS"

Left the box overnight just to see if it was busy. Still displays "Booting..."

What's the next step for this? I assume I should boot it into one of the maintenance modes, but which one?

Please contact support, they can remote access to check your system via Tech support mode.
https://my.netgear.com/myNETGEAR/support.asp

The below is how to access boot menu,
http://www.readynas.com/kb/faq/boot/how ... _boot_menu

Yeah... We'll see if we ever get to that. It's like pulling teeth making any progress. One response per day...

Well, we haven't heard a response on our ticket for 5 days now, so I'm turning here to see if we can get some progress. The last thing we were told was:

This is what I would like for you to try. Take the ReadyNAS with no drives in it and boot it in to tech support mode. If this comes up then turn it off and seat disc 1 2 and 3. Boot it normally now. When that has done booting. Turn of the device. Reseat Disc 4. And do a normal boot.

This sounded like a pretty specific procedure but since our RAID only has 3 disks, I asked for clarification on the procedure for a 3-disk system. The case #19985185.

It's not clear where he's headed in this line of debugging. He seems to think that more than one disk is bad, but that seems pretty unlikely. There were clear indications of a single disk failure leading up to the time when I replaced the disk with a new one. Now with the replacement, the thing won't boot.