If you do the holding the power and volume button for 15 seconds and it doesn’t work, try to leave it somewhere that is not hot or too warm for an hour. This helps your tablet or any Samsung device cool down. You might ask why and the answer is simple. You have basically left your device in an over heated place or you have used it nonstop and it has started to heat up, making your device over heated. This happens to me all the time and it’s completely normal. So I hope this helped you guys and I hope this fix’s your problems with your device no turning on or turning on and off.