iMac backlight turns off above brightness level 2

I've been using my iMac 27" mid 2010 as a very expensive mirror in my bedroom for the past few years and I figured it was about time I try to fix whatever the ****'s wrong with it. The backlight appears to turn itself off when I increase my backlight brightness to anything more than two bars, and when this happens I have to press ctrl + shift + eject to force the backlight shut and then hit any button to make it work again. I hope this is enough information to get the ball rolling! 🙂