Having trouble opening this light fixture to replace bulbs. The blue/white glass appear to be one piece. No visible screws or on base. I tried twisting it open, but whoever installed the box behind it did a poor job (old work box) and now one of the butterfly wings is collapsed and it’s half-falling out of the wall. I need to take it apart to re-deploy the old box wing, but right now I can’t open it at all. It’s probably 20 years old.