Try starting it up in "Safe Mode" and see if it will start up fully. If it does, while it will have limited access, you then know it isn't hardware but software. Perhaps there is a bad app, virus, malware, etc. You would then have to remove the problem item. Then it should start normal. However, if it won't turn on even in "Safe Mode" then it may well be either the OS software and need a "Hard Reset" or it could be software.
To get into "Safe Mode" please do the following.
1. First turn off the tablet.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something...