Yes all the time most of the functions can be ok and the screen black but still to be a mother board problem, but as long as you can blind touch on your screen seems the mother board to be fine and the lcd parts to be faulty. As Cody said the 100% sure is to test with another mother board, but i am very sure is the lcd in your case. "Please test the functionality of this item.........." means you need to try and plug the lcd on the logic board and see if the lcd is working properly without taking any plastic film away from the lcd or breaking any seal. If the lcd is not working you can send it back, but if the lcd is not working and you took plastic films out you can't send it back.