Microwave won't turn on

If the oven is completely dead it might be due to a fuse. Most ovens use a 15-amp ceramic fuse found under the cover. Two problems, though. First, the fuse seldom just goes on its own; usually something else is bad first, which means other troubleshooting and parts replacement. Second, many microwave oven covers are held on with security screws and you'll need to hunt up the appropriate driver.

If the oven has power but doesn't heat, the cause is usually failure of one of three main parts that make the microwaves (magnetron, capacitor or diode).

A microwave oven is not complicated to work on, but because of the voltages present and possibility of microwave leakage if a repair isn't done correctly, there is an element of risk involved. Unless the oven is a very high-end model or a built-in or over-the-range model, you might want to replace it instead of repairing. Like other appliances, they are inexpensive and repair often comes close to or even exceeds the cost of new.

Hope this is helpful.