Gilligan was looking his already short patience and was about, for the millionth time in his life, to just give up and go to bed. But first he figured he had to do things right one. If he was gonna solve this puzzle, he first needed all the pieces. He never actually gone through the center doors staircase. So he descended the stairs, (hopefully for the last time) and placed down the hall to ascend the center staircase. 

He had a sensation of disturbing deja vu as he climbed the eerily similar staircase and lifted the new trapdoor.