Microwave keeps blowing fuse. When I start the microwave, it starts to make a buzzing sound then

Question

When I start the microwave, it starts to make a buzzing sound then blows internal 20 amp fuse within seconds. What could be the possible problem and is it worth repairing?

Thanks in advancethe microwave made a buzzing noise and went totally dead. I replaced the internal 20amp ceramic fuse and set it for 1 second and it buzzed and blew the new fuse.