ok, I have all 3 keys, cleared all rooms of sand or bricks, can't open last chamber. Can someone help. I have retraced all steps, touched all walls
There is a secret passageway outside that runs parallel to the right side of the building.
Screen maps: https://drive.google.com/file/d/16kXvAcmsWkLaGAWFJdZBRfSXFwdERpVQ/view