I tried doing that but still no luck - it just doesn't even power on at all. I searched the net and found a thread where someone had to disconnect the battery for a few seconds, connect it again, and then it would boot again (like me, from a SD card).
So....I got the back cover loose - couldn't get it all the way off due the microSD slot. Noticed the battery leads in a cutout in the metal. Could get that dang thing loose, but I did manage to get the ground wire off there for just a few seconds and then put it back. Bingo! Booted a SD with 10.2 and gapps using TWRP and got everything back to normal again. Whew!
I'm quite familiar with electronics, and every piece of hardware on a PC down to the component level doesn't bother me, but I don't know anything about the Nook hardware or software. I feel like I just got very lucky!
Thanks again for your tutorials, scripts and answers here on the forums!