Hey Alan, Google exist, do you know ?
I googled for 3 seconds and I found someone who coincidentally posted the same question with the same microwave.
I give the link: https://www.ifixit.com/Answers/View/58160/Door+will+not+open+after+pushing+door+button
Do as mayer say do not attempt repairs on microwaves its really dangerous.
I am almost sure that this series and brand of microwave do have a programmed obsolescence that after a certain time the door will brake, the mechanism is probably build and designed with poor plastic, as result it brake after some time. (1 2 days after warranty I guess xD ).
Tough luck see you.