Plug in the smartphone and let it charge for hours. Then turn it on. If this doesn't work you've to contact the manufacturer support, you're likely to be received a defect battery piece.
Okay. I was very unsure about removing the back cover of my asus tablet me173x to detach the battery and wait a few minutes then press it back in. After 2 days of trying everything else which includes pressing and holding the power button, then the power and volume button together for long periods of time. I just knew it had to be the battery. The battery went dead and my tablet wouldn't come on no matter what I did. So i carefully opened it up after watching a video of a Russian guy taking my tablet apart and seeing how he lifted the battery. I did what he did with the battery, waited a few minutes and voila!!!! Back in business after plugging in charger it came on within minutes. I'm posting this because I was so happy! I thought my tablet was dead after 1 year of use. I hope this helps someone. Good luck
Stick a paperclip in the little hole at the top next to the ear phone jack. Push it in and hold it at the same time pressing the turn on button. Hold it for 10-15 seconds and it should come on. If not then hold it longer.