A while ago I received an old iMac from a friend of which the HD was broken. The machine was covered in a thick layer of dust, so badly the CPU/GPU fan was completely stuffed. So I decided to remove all the parts, and brush them clean. As a result of this dusty mac it also had the classic brown spots on the screen. So after cleaning this little menace I assembled it again with the result of.. a boot loop. LED#1 lids when plugged in, when pressing the power button LED#2 and #3 show (without the screen installed) and after 2 seconds it goes back to LED#1 to repeat the procedure until I pull the plug. I "baked" the Logic board and after that it got it to work for 1 day. So I wonder.. I don't expect the PSU to be broken, because when I hold the power button it stays on longer and the fans kick in overdrive.. anybody had a similar situation? btw, cleaning the LCD is, in the end super easy. I once saw a video on youtube (and about the only one online) of a guy doing the same with a 27" LCD.