One more thing to try: when fully closed the lamp door pushes a failsafe pressure switch. Some time back the plastic at the screwhole on mine cracked just enough that the door was no longer pressing the switch with enough pressure, and I was getting a similar symptom. To test, examine the door to make sure there isn't a broken pin, and then set the projector on a couple of books so you can access the door, turn it on, and then press the door in by hand; if the projectoir comes on and lights up, you've traced the problem to this door.
Drove me nuts until I discovered the problem. The permanent fix involved a bit of epoxy