Emerson microwave ovens have a line fuse that protects them from too much electricity. If the line fuse is blown, the unit stops working. Replacing this fuse requires pulling the outer cabinet to access the fuse.
Once the owner locates and removes the fuse, he should test it with a multimeter. With the meter set to Rx1, the display should read O ohms when the ends of the probes touch either end of the fuse. If the fuse gives any other reason, it is defective and requires replacement. Before replacing the fuse, the person testing the fuse should determine the underlying problem because replacement fuses typically continue to blow until a repair is made.