After Killing the Turret Sentinel, the laser activates.
This kills me and resets the puzzle, though it shouldn’t. Looks like others in the forums are having a problem as well with the laser going off prematurely.
Edit: Doh - can’t create a link in my post, but here’s the end of the URL for the screenshot (add the http back).
snag.gy/nTlCy5.jpg