Press the 5 tiles in the following order:

-=Back Wall=-
1. Middle tile
2. Left tile
3. Right tile

-=Side Walls=-
4. Left wall tile
5. Right wall tile

This will give you the blue stone, which goes into the hexagonal spot in the 
ceiling. Light will show the order of the symbols on the stone ring below:

 Outer ring  : cow head
 Middle ring : jar
 Inner ring  : leaf

Remove the blue stone from the ceiling and place in into the center of the 
stone rings -- wait a sec -- this should do it. Good luck!