ReadyNAS NV+ v1- boot troubleshooting

Hi, I've read all the boot hang threads in the forum and have a game plan to troubleshoot my own boot hang, but before I start, I want to have a plan a, b, c, etc. and I have a couple of questions to try to maintain my x-raid data.

First, this is what happened. My NAS has been humming along happily for 4.5 years. The other day we had a brief 2-second power outage...enough to make the clocks all go back to 12:00. That night or next day, I noticed my HTPC was not able to connect to this NAS.
I have two ReadNAS's both connected to the same UPS. The NVX was fine, but this one said it was waiting for IP on the LCD. I could see it was hung up there, so I shut it down via the power button. Then restarted it. Then it just hung at Booting - Please wait. Now the only way to power it off is to pull the plug. I received no error emails prior to this event so I know whatever went wrong was instant.

So now I will troubleshoot.

1) Power off, mark disc locations and remove all disks and test each one with the diagnostic tool. Hopefully only one drive is bad, if any.
2) Try booting with a spare good disk.
2) If hangs, power down and try booting into an OS reinstall from flash.
3) If still no successful boot, try an OS install from USB image. This is where one question is. I don't upgrade firmware if I'm happy with the one I have, and I was, so it's on a very old one- v4.1.7. I don't see where I could get an image of this version anymore. So if I upgrade to the latest radiator version in this step, will that screw up the readability of my good x-raid drives when I re-install them? Or will this be ok to do?
4) If I can get it to boot on the spare drive, then power down, re-install just the good raid-x drives in their original locations leaving the bad one out and boot up on them (fingers crossed).
5) If it boots, hot-add a new replacement drive to sync into the raid.

Another question. Let's say all the diagnostic tests find all drives to be ok.
Then I was thinking I would try booting it with 3 drives in at a time (always in their original positions) to see which one is causing the boot issue. This should still maintain my data, correct? It won't boot on the bad drive, and when it does boot, it will be just the same as step 4 above so figure I am ok to test this way, yes?

I doubt it is the momory, but I'll run that test too if no success.