Uh oh...voltage crash and now won't turn over

Ok gang. Finally able to wrap this up. Followed 67dart273 testing guidelines and found to be a bad alternator. Oh and the reason it wouldn’t turn over was a faulty neutral switch. Fixed that too.
Took me a couple days of nonexistent time but we’ll worth it.
Thank you guys, as always it’s nice to be able to have this kind of support when you’re scratching your head.