Replacing the opening lever, door hook, internal button spring or door opening button are the four ways to fix a microwave door that refuses to open. Repair is not an option for any of these parts.
The opening lever on a microwave door actually pushes it open. If this lever has broken, when the user pushes the button, the spring acts against the lever, but the lever cannot push the door. The door hook also is designed to release when the door opens, but if the hook has broken, it stays in place and bars the door. A button spring behind the button can break as well, so pushing the button does not act on the lever or hook. If the button breaks, a similar problem occurs.