so randomly, my car wouldn't start. It's as though the battery is super low. It clicks, but no dice.

Okay, the obvious- it's not the battery. everything else works perfectly.the gauges act fickle, it's almost certainly a ground- but what ground?

Everything works (lights, door chime, radio, etc) except the gauges bounce around (though generally work) and after pulling on cables and banging around on the starter, the indicated voltage changes. after a few hours, it starts up.

Starter? Something else?