In my 2009 standard prius, the back up camera often, maybe 50% of the time, is just black. It has some scrolling look, and sometimes i can see a fiant image of whats there. The warning text on the screen is still there, and im positive the is plenty of light, and nothing blocking the camera. Its almost as if the TV rabbit ears need some adjustment. Flickery images, images literally scrolling left to right, etc. Other times, its perfect. Where do i start? loose wires somewhere?
Have you checked to make sure the camera lens has not been pushed in? There are reports of that happening posted somewhere on this site.