Amazing what one can find on the InterWebs!
I've just gone down this exact same path you did, with the same refrigerator. The evaporator fan checks out fine but it is not getting the voltage on the yellow wire to tell it to run.
I studied that circuit board for awhile and I'm not sure my soldering skills are up to the challenge of replacing that tiny "FF" fuse.
What's the worst that could happen if I just jumpered it with a wire, or a 1 Ohm resistor like you did? Could I leave it that way indefinitely?

For now, I jumpered the red and yellow wires at the fan, so the yellow gets a constant 12v. That's getting me refrigeration so our food won't spoil this weekend. But that means, of course, the fan never turns off. What happens if I leave it that way?? Will it wreak havoc with the temperature regulation, the defrost cycle, etc.?

Whirlpool/Kitchenaid no longer provide the replacement circuit board, nor have I seen it in stock online anywhere. So the only option seems to be repair and/or hacks.

Thanks for any advice here!
Tom