Here’s how you can root Barnes and Noble E-reader Nook. It’s based on Android and the OS is stored in the SD card. To root the Nook, you simply have to extract the SD card from Nook then enable the shell.
I guess this is rather simple, not a real hack but still, you can do a lot of stuff once you root your Nook.
1. Turn off nook
2. Take off the back cover of the nook
3. Remove the battery
4. Remove the user microSD card if there is one
5. Unscrew all screws. Dont lose them. There is a hole in the bottom left with white in it. That is also a screw. Unscrew that.
6. There are a bunch of tabs around the sides of the nook that release the white bezel. Once released you will need to unseal the glue
7. Congrats you are 25 percent there!
8. There are two black tabs on the sides of the nook where the page turn buttons are. Push those back to unlock them
9. You should be at the board now. Find the OS microSD card
10. Remove it
11. Place the microSD card in a adapter, then into a computer
12. Mount it as ext3 read-write (sudo mount /dev/sdb1 /media/disk replacing values as needed)
13. Open the file init.rc as sudo (sudo nano init.rc)
14. Find the line that starts talking about adbd
15. Replace the first occurance of the word disabled with enabled
16. 50 percent done!
17. Eject SD card
18. Put SD card back into nook
19. close nook up
21. Now, on a computer again, download the Android dev toolkit (google it)
22. Open a terminal
23. cd to the android folder
24. cd tools
25. ./adb connect IP_OF_NOOK:5555
26. ./adb shell
27. If you want to disable updates from B&N run: mv /system/etc/security/otacerts.zip /system/etc/security/otacerts.zip.bak
CONGRATULATIONS! YOU HAVE ROOTED YOUR nook. Have fun, be safe, dont forget to bring a towel