I. Before You Begin
1. This will erase everything off of the Nook Color and return it completely to stock (the way it was out of the box).
Thanks to Samuelhalff for the stock nook images! Original post can be found here. Please thank him/donate to him if you appreciate his work!
II. Create a Recovery Image SD Card
1. Download the Clockwork Recovery image FOR YOUR MEMORY CARD SIZE and save it to your computer (original post found here).
2. Extract the file somewhere on your computer. (You may need to download WinRar to extract it, Google it).
3. Take your MicroSD card and put it into an external sd card reader then plug that into your computer.
4. Open WinImage (the flashing program from our How To Root procedure) and select Disk > Restore Virtual Hard Disk Image on Physical Drive and select the SD Card/SD Card Reader and then select the Cwm .img file that we unzipped earlier and wait for it to finish.
III. Flash the Stock Firmware
1. Download the latest Stock firmware ROM from here and save it to your computer.
2. Copy the stock ROM (and leave it as a .zip file) to the sd card you just flashed using WinImage. Put it on the root of the SD card, NOT inside any folders just on the sd card itself.
3. Once it is done transfering, remove the sd card from the computer.
4. Turn off the Nook.
5. Put the SD card inside the Nook while it is off.
6. Turn on the Nook.
7. You should be greeted by the Clockwork recovery screen, on that screen select mounts and storage and select format system, then select format data.
8. Now make sure system and data are NOT mounted (they will say “mount system” and “mount data” if they are NOT mounted).
9. Push the power button to go back, then select Install zip from sd and then choose zip from sd and then select the stock nook ROM we put on the sd card earlier and wait for it to finish flashing. It will take a while.
10. Once it says install from sd card complete, turn off the Nook.
11. Remove the sd card and then turn the Nook back on.
IV. Reformat the SD Card Back to Normal
1. After the Nook has booted back to the normal homescreen, put the sd card back into it.
2. Then on the NOOKColor, go to Settings then Device Info then SD Card then click Unmount and then Format. Once it is done, it will remount the SD card and you will be good to go!