Starts when opening it

Our old Carousel microwave now turns on when you open the door. The display hasn’t worked for quite sometimes now, so I don’t know if it’s showing anything. The microwave still rotates and heats things up. Just wondering why it would turn on when I open the door and what to do about it.

Hi.

Unplug the unit.
Open the control panel. You should be able to see door switches on the left.
Mark the wires, take them off and do the continuity test.
They marked C, NO, NC. Test them with door open and closed.
For the parts research provide the complete model number.

Thank you.

Simon.