OK then. I'm willing to accept an entry in a fictional book quoted in an inaccurately named "trilogy".
So, working from there we find in wikipedia that "work" does not include the transference of "heat" energy since there is no macroscopically measurable force, only microscopic forces occurring in atomic collisions.
So as far as being a robot, the microwave oven is right out!
It still doesn't discount the 5 year old as being a robot. Though it has yet to be proven, it is
technically feasible that this child could do the "work" of a human.

I guess it could come down to;
"What constitutes a mechanical apparatus?"
and "What constitutes 'programing'?"
BTW: I have now discovered that there is an International Standard (ISO 8373) that defines a robot as -
"An automatically controlled, reprogrammable, multipurpose, manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications."
I couldn't consider this
THE definition of a robot though, as it specifically says "for use in industrial automation applications" and there are quite a few "robots" available that are NOT for industrial automation.
Heck, according to ISO 8373 non of the "bots' used in "Battlebots" would be considered Robots because they aren't "programed"