Unlocking the second mechanism requires solving a short puzzle.
First, click on one of the three Locking Mechanisms. The line of runes on the floor between it and the Master Locking Mechanism (center) will become clickable. Look at the rune on the stand beside the mechanism, and click the matching rune on the floor. (It will glow purple.)
Now, click on the locking mechanism again.
If you matched the rune correctly, you should see a message: The Locking Mechanism has been properly attuned! A line of purple fire will appear. Don’t walk across it, it hurts! 😉
Once you’ve matched the runes on all three locking mechanisms, you’ll see a message:
All Locking Mechanisms have been attuned!
The Main Locking Mechanism is ready for activation!
The barrier around the main locking mechanism will fall. click on it to complete the quest.
While you’re in this cave, look for the force ghost to complete your “Speaker for the Dead” title!