My Nook HD is charging fine and holds a charge. However, I have to press and hold the on/off switch multiple times to see it reboot to get to the screen. During these attempts, the screen will light faintly then go black. Problems started when the wallpaper changed to yellow swirls, the letters under icons/apps are very hard to read, the brightness is turned up all the way, and the letters when reading a book for night mode are yellow on black. Background has dimmed. B&N Help was not helpful. I can't find ANY thing like this on the internet for help on this issue. Any advice?