Sorry, I don't have any suggestions beyond what you have already tried but you might get better response if you posted in the HD/HD+ forum - this one is for the older Nook Tablet. I also don't think your problem is related to the battery.
Try holding the power button until it hard powers off, leave it plugged in for 15 min, then bringing it back up. I have resolved this issue on my by doing this trick. When it comes back up get a free app called "Clean Master" Here is a link to it. https://play.google.com/store/apps/details?id=com.cleanmaster.mguard&hl=en