Chances are the metal baffle on the door is a bit too close to the place where it inserts itself. I would take a miniature screwdriver and gently probe that opening (with the door release, of course, 'open'). I forget, but you just might have to take the top off in order to (possibly) see where the impediment is if mere 'closeness of fit' is not the reason for not readily opening. It is not too difficult but it is necessary to be careful. - David Lyga