If you have the stock recovery, it should try to reset itself. When the nook logo first comes up, hold the power key and the n key together for about 5 seconds and release. It should boot to recovery, either the stock recovery or the CWM /TWRP version.
Sent from my Nook HD+ running CM10.1 on emmc.
Now I've done it many times, nothing changes. I still see loop boot ((
may be damaged the internal partitions?