I found some directions that might help you get this problem sorted.
Charge your device for at least 30 minutes and try to restart your device again:
- Press and hold the Power button for 40 seconds.
- If the device restarts before 40 seconds has passed, release the Power button.
- If the device doesn’t restart, release the Power button, and then press the Power button again to turn on the device.
If the issue persists, attempt to Factory Reset using the built in device recovery mode:
- Power device down completely via the Power Button. If the device is unresponsive to the 2-second Power Button press, attempt the 40-second Power Button press, which should cause full shutdown.
- Make sure your device screen is completely off with no activity.
- Enter Recovery Mode by pressing and holding Power+Volume Down for 5 seconds.
- Once in recovery mode, use the volume keys to navigate to “wipe data/factory reset,” and the power button to select it.
Please note that a factory reset will remove any content you have downloaded to your tablet.
Hopefully that gets your tablet going again!