What did Thomas figure out about the Maze during the Changing?

Thomas figure out that In order to unlock the portal at the cliff he needs to insert a special electronic chip that can be found in Theresa's, who is a robot, head. Theresa revelas that she has become more than just a machine an has feelings for Thomas, and because of that she gives him the chip willingly from her hard drive. They then begin preparations to go through the portal.