Hi guys, So my iMac 27" set itself to max brightness, and nothing I have tried can turn it down. I have tried a PRAM reset, SMC reset, permissions repair, cycling the power. Nothing has worked. Obviously the keyboard F1 and F2 buttons don't work and the slider doesn't work in the Display settings either. I really need some help here, I'm hoping it isn't a hardware issue because I simply don't have time to sort it out at the moment. Cheers.