Where does the electrons go when a short circuit occurs

At the level of an individual electron a short-circuit doesn't look much different than a normal current path, it will move because of the electric field.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.