This solution - to press and hold the Power button and Volume Up button at the same time didn't work for me. It worked months ago when the screen of my Tab S T-705 was freezing while it was switched on and for almost an hour I was wondering what to do... then I found this forum which helped me to solve the problem!
...but now, this trick just don't work for me. I hold both buttons (Power + Volume Up) for a minute or so and even longer but nothing happens.
Yesterday, I noticed that I can't switch on the WiFi and Bluetooth and also while charging the tablet, it was very hot, more than usually... and losing power very fast. I was thinking today to reset all to factory settings, but I was surprised by the black screen and I don't know what to do.
I bought it Feb 2015... I think, my Tab S is Too Young To Die... don't you think!?
Oh, I forgot to mention that when I try to charge the tablet, nothing happens as well... it's like a dead piece of plastic now, WTF!?!