Last night while heating up a snack we heard a loud pop and then everything went dead on the microwave. Nothing lights up or displays at all on the Microwave.

The internal 20 Amp fuse is blown.
I checked the Magnetron for a short to the case or open and both are ok. I do not see anything on the circuit board that looks like it blew.
I checked the large transformer for a short and it appears fine.

Any suggestions for what else to check?

Thanks