This might not be ASB, but an excellent explanation is needed here. Swiss Nazis were weak and disorganized, I recall that one party wanted to kill Hitler for his pact with the Soviet Union. A more cohesive, powerful and determined effort might have done something, but I need to know HOW this happened.
Switzerland had 12 pro-Nazi parties, with a total of 40,000 followers. Apparently they were deemed too crazy (at first) to be much of a threat by the Switzerland government.
The Nazi parties really weakened after, in 1936, a (Jewish) student from the Bern University shot Wilhelm Gustloff, head of the National-Socialist Party in Switzerland.
Then the Nazi parties exacted revenge by killing a lot of Jews, and this turned Switzerland on. The government created some sort of Federal Police to flush out subversive activities, which resulted in most of the Nazi parties being banned. Then they refused to nominate a replacement for Gustloff, and this chopped the snake's head off. Then Switzerland mobilized.
The PoD would be that Gustloff doesn't get killed off. But I doubt that would do anything about the strength of the Nazi parties, but a least they could still dabble in Switzerland's politics, then after the Fall of France...