Before anything else confirm that the tablet is charged . A dead tablet will turn on just long enough to shut down . If the table is completely charged and your still having the issue then disconnect the battery for a minute then reconnect and reboot. This guide should help show you haw to disconnect the battery
[guide|56751]
This video shows as well how to open the tablet as well as disconnecting the battery . you dont need to remove the battery as your not going to replace it
https://www.youtube.com/watch?v=sZG28TPmd8Y
Hope this helps