The "F3" error code means a shorted key panel.
Inside the control panel suppose to be a wiring diagram which should help you to diagnose the power failure. Besides the line fuse there are two more thermal fuses - one to control the magnetron temperature and another one to control the cavity temperature.
- The part number for the key PCB assembly is
AP3792788
- The part number for the inline fuse is
AP2631556
Gene.