Well, first I'm curious about why you want to open the case.
It should be done by a competent watchmaker.If you really want to do this, a case knife should lift the case top off the case. You will note that the only access to the movement is through the top of the case. I don't remember if there is a particular place on the case where the knife blade is supposed to be inserted. Anyway the top of the case separates from the resin part. Good luck and I deny any responsibility if something goes wrong with this exercise.