infocus lp 420 no picture?

i have got 2 infocus lp 420 that i was told that the bulbs had gone so i brought 2 new bulbs and they still do not work. they both power up and and the fans run on both if i press the menu buttom on one of the projectors all lights turn green? but the other does not do this, i have tried holding the left mouse button and menu at the same time but does not seem to work.

any idears? could it be the psu and if so what normaly goes down on them

thanks