Samsung Galaxy Tablet Won't Turn Off, Won't Turn Off, Charging Icon Shown

I had the Samsung Galaxy tablet hooked up to the charger and plugged into the wall.  Left it there for a day or two.  Went to use it today.  It wouldn't turn off.  It wouldn't turn on.  Nothing. Nada.  All that the screen showed, was the charging view or charging icon.  But it was stuck.  It looked like the tablet was hung.

Obviously pressing the power switch didn't work.  I googled but nothing jumped out at me.  I pressed the power button and huge volume button next to the power button, and held them down for 10 seconds.  To my surprise, the charging icon disappeared.

Then I pressed the power button again and held it momentarily.  The thing booted.

I hope this helps someone.