I am posting this here because nothing else makes sense

Somebody already asked but did you disconnect the battery before working on the switch? I tried installing a stereo (cassette so it was a while ago) in my 1970 Duster years ago and while lying upside down under the dash there was a big flash and I never found out where it came from. It wasn't the wires I was playing with at that moment. Now I disconnect the battery every time I do anything no matter if it is electrical or mechanical.