OK I am assuming you mean it won't turn on but is charging? Or are you saying it won't turn on and won't charge?
First... either way.. if the device is under warranty still, I would contact the manufacturer before doing anything to it. Don't want to void the warranty. This includes the info I am going to put here.
Try the following and see if it will turn on.
A. Test the charger cord to see if it is good. Either try your cord in another device, or try another devices cord on your device.
B.
1. Remove the battery.
2. Press and hold the "Power" button for 20 seconds.
3. Now put the battery back in.
4. Plug it in to charge and allow it to fully charge before turning it on.
C. Should that not be the problem, then check the battery to see if it needs replacing.
And yes, I do know that batteries can be a real pain to remove in tablets. However if it needs to be replaced/removed and isn't under warranty, it may be necessary. There are many videos online about how to do it.