If the microwave appears dead, this could indicate a problem with the Line Fuse, which will blow if excess current is being used by the microwave components. While this fuse is easily replaceable, there may be other issues that are causing the appliance to over-draw power. There might also be a problem within the High voltage circuit of the microwave, in particular with components such as the diode, magnetron, high voltage capacitor, or transformer. Other factors that may cause this condition include a blown thermal fuse that should be tested for continuity or Thermoprotector that has tripped. (This is a small component that ensures that the microwave does not overheat.) Certain microwave models may require the system clock to be set before they commence functioning.