Black Screen, Inverter Board or Backlight Bulb

Yesterday night while I was using my pro, the screen suddenly turned black. First I thought the screen might be broken. But when I take a close look today I saw the screen show thing but no back light. I plugged it to an external screen and it works just fine. I talked with one local computer repair shop and they told me it is either the inverter board failed or the back light bulb failed. Since the back light bulb is part of the screen and I have 3 year warranty on the screen(just screen, I replace this spring). I just wondering if there are anyway I can test inverter board see if it failed? my screen does show things but just very dark. barely can see anything. the little apple sign light on the cover is not turn white when my pro running. Keyboard back lights works fun. everything else works fine except the screen is dark. I really need to fix it ASAP! I am typing on the floor it really bother me. I can't going to class with out my mac. So PLEASE help me out guys! Thank you very much!