camera not moving

Does anyone know what to look for in the event that the camera does not dance up at all during startup? I keep throwing parts at it but getting expensive. I wish there were an app or something to help diagnose drone issues. Anyway, not sure it i should be looking at the bird or the camera...

My friend has a phantom 4 pro which crashed and it seemed like only the yaw arm was broken and the flex torn. I bought both new parts on ebay and replaced them and now i can't move the camera anymore. It's just dangling there. The video stream works fine though. When i turn it on, the camera...