Frozen screen will not shut down

try this How to Completely Reset Your RCA RCT6103W46 Android 4 2 2 Tablet

Push the power button to shut down, then do a reset.

Try shutting it down or re booting it. If all fails try re formatting it

When was the last time the tablet was turned off (not just put into sleep mode)?
To turn off the tablet, hold the power button for two or three seconds, then tap "shut down" when asked if you want to shut down your Kindle.
After the device has completely turned off, press the power button to restart.

Please reply with more information if this did not fix your problem!

See the following page for more information:
Quick Fix Slow or Frozen Screen

Rebooting is easy. It is called a hard reboot. Just hold both buttons down until you see a red slider, and then slide it to shut down. It will restart, and you will see the Apple logo.

If your kindle are frozen and won't turn off so, firstly reboot your kindle this is done by pressing the side button minimum 20 to 40 second and screen are blinking so, give the kindle about one minute to start backup.
What to do when Kindle Stuck on the Start screen

Either wait for it to die completely and turn it back on or hard boot it (holding down the power button till it shuts off).

hold the re-set button down until the tablet shuts itself down if you have already done this and it does not work and you have had your tablet for less than a year usually the company will fix it for free or send you a new one free of charge because it is a problem with tablet not something you did.

TRY a hard reset on the Nook if that doesn't work i know of this fantastic site BNTPrice.com that sells them for cheap. i hope this works for you

1. Press the "n" button to display the quick nav bar.
   

2. In the quick nav bar, tap the Settings icon.
   

3. In the Device Settings section, tap Device Info.
   

4. Tap Erase & Deregister Device.
   

5. Stop. Think. Think again.
   

6. If you really, really want to do this, go to Step 7. If not, tap the Back button.
   

7. Tap the Erase & Deregister Device button.
   

By holding the power button down for about 10 seconds it rebooted