Locate the bottom screw which holds the metal frame around the lamp and unscrew it. Because there are no other screws to hold it, gently lift the frame upwards to unlock the pin on the top.

Be very careful when unhooking the four small metal clips because they can easily break (if you break more than two clips, the front glass will become loose and water could enter and fade the inner surface of the lamp). After removing the glass carefully, place it aside and remember to clean all of the surfaces before reassembling.