relatively new NOOK..has been acting weird.... not too soon after getting it, it shut down and rebooted..had to re register and reload everything. Does seem to take along time to turn on...last night would not turn on unless on charger. Now it won't turn off whether it is on the charger or not...grrrrr.
If you're within the return window, bring it in to the store to see if they can help or just exchange it.
My first HD+ was having an on/off issue as well so I exhanged it.