Just to confirm, you are sending us pictures of an open fixture and asking us how to open it?
If so, the third picture down seems to have a metal lip that pushes against the glass and holds it. Maybe just pull a bit harder?
Also, I see a bolt with a corresponding hole but that would be too easy so I'm guessing that's not it. Maybe the receiving threads are not normal and you just turn them a half turn to make them unlock, then another half turn to lock.