When Alec finds his flashlight, he puts it on and reveals the Berg nestled inside the room. Jackpot.
They run over to the hatch door, only to hear the struggling outside of the door vanish. At first Mark thinks this is a good sign, but then he realizes it's just that the people are up to no good.
Alec gets the hatch door open; they walk inside, and they find three workpads.
Just as Mark is taking a look at one, he's thrown to the side and the workpad falls.
One of Bruce's people most likely pushed a button somewhere, opening the landing pad… which then causes the central chamber to rotate open.