I recently purchased an Lenovo A1000 tablet, and everything has been working fine. Last night I turned it off completely so the alarm wouldn't go off on my day off. However, the alarm did go off, and now I can't shut it down! It's been ringing for a little over an hour, the screen is on, but black. I have home buttons, but they won't work. Power button does nothing, and volume buttons do nothing. Any ideas?