Rear camera issue

Looking for advice on why my back up camera isn't working. I have a 2008 with an aftermarket camera. It worked for years before, then one day, it started to intermittently not work, and then completely stopped a couple months later. I figured the camera unit was damaged or wiring got damaged, so I replaced the whole thing up to the head unit, all wiring installed exactly as it was before, but it still does not work. Reverse activates the camera, but I still get a no connected error. I'm getting power and ground from the reverse light, but also tried powering it from the head unit wiring harness with the same reault. I've checked connections a few times on both ends, I'm at a loss...