Hello, this happened to me. Problem is those tiny resistors or caps next to connector. They are broken or lost solder connection when you install the cable back on. If you accidentally sit the camera cable wrongly too close to the cam, you will push the connector againts the tiny caps there. On my repaired phone one of these caps was totally lost or only connected with other end and twisted 180 degrees.
Most likely one of those tiny caps right next to the camera connector causes all your issues. It is very easy to break while sitting the camera cable on it's place.
Here is image where I added solder: http://but.fi/36x