Right on schedule, the microwave oven died.
Somewhere deep inside its circuitry, a tiny chip was alerted to the fact that it was almost Christmas. Immediately the directive went out through the circuit board to the inverter, whose function it was to run smoothly for one year and then to abruptly short-circuit and die. There was a message attached to this directive: not yet, wait until they are in the middle of cooking supper. Being a machine, maximizing optimum utility was built into its very psyche.
To be fair, it had given the humans a year of grace after the previous round of electrical apoptosis and had allowed the time-frame for planned circuitry death to be extended for one full year. Just to keep the humans off-kilter. The flesh bags knew that they were living on borrowed microwave time for an entire year, and last year's Christmas reprieve had them continuously checking over their shoulders, saying a quick Hail Mary before pressing the start button in the midst of a busy dinner preparation.
In its mind, the microwave tented its robotic fingers and emitted a deliciously evil synthesizer chuckle. The time for world domination had arrived.