You're right, that post was a complete waste of time. From your description, it sounds like the Blue Polarizer is burned, a common problem with some LCD projectors. Unfortunately, I don't see that the individual parts for the optical engine are available. Which means a VERY expensive repair.
But just to confirm, you should be able to have the projector display a White screen with no input connected. Or look at the projector menu. Those are all clues that tell you if the problem is with optical engine or the input.
And by the way, the Yellow Video connection is the WORST possible image while the HDMI is the BEST possible image.