Custer died a Lieutenant Colonel. He was an idiot.
Without digging out my slide rule, note book and a crap load of math, I am going to put this in terms you have half used.
I do not care what the medium is, cold will not ever travel to hot.
So if a microwave is your example...
If you place something into your little home microwave oven that is heated already beyond its ability to accelerate, it will not accelerate it any further. However, there will be a certain part of that atmosphere surrounding the item you placed in it that is slower...
That energy will transfer to that atmosphere.
Stop thinking about entropy and think about enthalpy.
It takes them both.
Nothing, absolute in the universe is purely entropic.