I got my 1st gen (?) regular black and white nook (with touch bar on bottom) deregistered, finally. My steps are as follows. I think you can skip the wifi thing and do the factory reset, but I'm not sure.
Prelude - may not be needed
1. Connect to Wifi. The error message says you can't deregister without it.
2. Load up example.com and verify the wifi works.
3. Mine didn't even deregister once I connected the wifi.
4. Sent an email to the owner since apparently BN phone support refuses to reset old Nooks.
Main section:
4.5. Attempt the factory reset by doing the power button + 12 second hold thing 6 times. I must've messed up holding it down once, because:
5. After a few restarts, apparently it downloaded a firmware update while it was on the wifi? Clever, ornery device.
6. It got stuck in the restart / install sequence. After several hours of waiting, I went back to trying the restart method.
7. Eventually, the touch screen showed "Restoring to Factory Fallback..."
8. I had the normal factory fresh experience. I didn't have to do anything else. Apparently G1 Nooks (or early firmwares?) let you bypass registration with just a menu prompt.
In theory, a hack could open up the Nooks the same way the Kindles often are. Seems like they're much less popular in general and among hackers. Would something like this be relevant?
https://www.mobileread.com/forums/sh...ad.php?t=92223
https://www.reddit.com/r/nook/commen..._a_hard_reset/