What to check

The camera is 12v DC and always ON. Measure for 12v DC on the Red & Black wires going to the camera.

If you have a test monitor, check for video output at the camera Yellow & Black and on D1(-) & D2(+) on the 500-LSV pcb output.

Corrective Action

Replace Camera and OR 500-LS

Links

https://www.entryphone.co.uk/shop/productdetail/PCB-500-CAM

https://www.entryphone.co.uk/shop/productdetail/PCB-500-LS