Went through a box of fuses testing out different things, after fully dimming the interior lights and reconnecting it started working, but this coincided with opening a new box of fuses. After reconnecting everything it still works. Unless that box of fuses was somehow "defective" and the fuses were prematurely blowing, I've probably got some intermittent problem that'll pop up again, very annoying. I checked everything that seemed reasonable to access.