Update.
Got it started by jumping the starter, ended up being a weak battery I was jumping with. Putting jumper cables on the mower's battery wires and trying to start does nothing. When I put the negative on, something clicked around the carburetor but the motor didn't even try to turn. Before if I put the cables on the battery it would do the same spinning once and stopping thing even when I put the ground on the engine. Anything I can try so I can actually use the key to start?