Oh, okay, not the conclusion I was expecting. Glad you got it sorted
I have seen this a number of times, and concur with the prime idead to adjust the postioning of the ADF.
When you have this problem, look at the double contact near the right rear hinge. Watch closely as the lid goes down....the contact closes on the way down, but that angled plastic block in the lid moves forward and the switch actually opens again as the ADF lid comes down to horizontal!