When the lift stops grab everything in the chamber and head through, take a left and go down the stairs.
As you enter the Chamber of the Hero, grab the medkits on your left and the pick ups behind the sarcophagus. As you approach, the wall will peel away; head through the hole and along the corridor.
The wall at the end will open and then the whole room will descend. Exit through the opening in the wall and follow the corridor round and down until you reach a block with the id logo on it - it will slide back and open a door behind to your left.
Carefully enter and grab the PDA in front of you on the altar. Go back out and head right and a cut scene will trigger.