It should be quite simple, just let the light of each mirror point to a downward mechanism. The first level is simple. There will be stone pillars blocking the second level, and you need to kick the stone pillars. On the third floor, first shine the light on the stone statue and there will be two doors. After taking the treasure, shoot the beam towards a mechanism similar to the one on the first and second floors, which is probably opposite the stone statue. Because that mechanism is inside, you'd better try it several times. It’s also worth noting not to rush too much. Wait until your partner is on the stage before moving. The light will last seconds. If you see yourself trapped inside and unable to get out, destroy the direction of the light first. Then after coming out, re-adjust the direction.