Originally Posted by
Bobster
You only need to create a tiny gap between the o-ring and the case for a fraction of a second to equalize the pressure because the volume of air inside the case is so small. With no knowledge of the particular case it's hard to say how to accomplish that. But whatever works, and hammer it is.
That explains it. I originally tried nailing into the case to create a hole and normalize pressure, but the polycarbonate was too hard, and bent but would not break. I guess the force of the hammer bent the seal, normalizing pressure, and popping the seal open.