Please make sure the tablet is charged for at least 4-6 hours. Also, make sure the correct button is being used, oftentimes we hear the back or home button has been used in error. If the issue persists, you can try performing a power reset. There should a power reset button near the charging port. It looks like a tiny hole. While plugged into the charger, use a paperclip to push the button inside this hole for 3-5 seconds. If it turns on, please allow it to charge for 4-6 hours before using it. If you leave it on the charger for longer than the allocated time, you will go back to having the same problem as before. If the power does not come on, please leave it plugged up for 4-6 hours then disconnect it from the power and turn it on.

If your tablet does not have the reset button: With the tablet plugged into the charger, hold the power button for 10 seconds then click the volume up once. If it turns on, please allow it to charge for 4-6 hours before using it. If you leave it on the charger for longer than the allocated time, you will go back to having the same problem as before. If the power does not come on, please leave it plugged up for 4-6 hours then disconnect it from the power and turn it on.
Support Troubleshooting Guide