Approach the shining sphere and pick it up. Carry it to the field found east from the entrance and wait until the robot stands on the tile. Use the newly created staircase to carry the sphere upstairs and wait until the robot proceeds to the next field, creating a bridge. Make your way through the bridge and bypass the pedestal (which is currently inactive). Reach the other side of the bridge and begin following the fox.
You are now standing before a challenging climb. Use the planks, ledges, and other protruding elements to climb to the top of the wall. Approach the large block and push it from the lit field to unlock the way forward.
Place the skull block on a special field next to the column. The object will move to the left - pick up the sphere and place it on the new pedestal. Jump below and move the previous block for the column to return to its original spot. Once that is done, push the stone to reveal a staircase leading to the pedestal.
Use the pedestal to create a large, shining sphere. Descend below and use your shout to begin a cut-scene. All bipedal robots have returned to life and will begin to walk in the same direction - follow them.
Follow the linear path to reach a new chamber in which one of the robots will stand on a special tile. Jump on a column and cast a shadow on the nearby wall to unlock the way forward. Use it to reach a previously visited staircase. You are now able to get past the key-shaped door - use it complete the third chapter.