I was using my Samsung Tab A tablet just fine, put it down then when I got back to it later, it won't unlock, restart, or shutdown.  Entering a PIN takes you back to the lock screen where it asks for the PIN again.  Holding the power button down brings up the Shutdown or Restart options, but when you pick either it asks for the PIN which just brings you back to the lockscreen AGAIN.  Also, I accidentally logged from my device list in my Samsung app thinking I could log in again. HELP! Thanks. ... View more