Hello!, Possibly have a short in the internal part where they go together with the RF shocks, if you dare you will have to open it in that part it is a bit complicated and you have to have some experience and if not try with a used one of another microwave They are very similar, what usually changes is the way of assembly.
Change the magnetron as I told you before and that's how it solves the fault, friend greetings.
Put the model of that to see if a replacement is achieved, anyway for the same capacities in liters of microwaves you can use several different. As I told you before, the only thing that can change is the way of assembly.