Thought battery was dead so I jumped it and it started. Tried to start it later with the same cables and nothing. Bought a new battery and charged it full. Nothing. Headlights come on and don't dim when I turn the key. The starter is not even trying to spin. What to look at next?

I'd try tapping on the starter with a broomstick or something while someone's turning the key. That or is it manual or auto? If it's a manual, there's a clutch safety switch bypass...it's one of the fuses, I just can't remember which one. Aside from that? Maybe the ignition switch is taking a dump. Those would be my guesses as to where to start checking.