Chosen Solution
I’ve replaced my screen and after, the display preferences changed and doesn’t say Retina anymore. also, the light sensor doesn’t work and the backlit keyboard shows no entry sign when trying to increase or decrease the keyboard light.
Sounds like an SMC and Pram reset are in order. The camera connector cable might not be at all the way. Apple uses the iSight camera to determine whether it’s bright or dark out. If it’s bright out, your keyboard will not light up and it will give you the no smoking sign. Cover the WebCam with your thumb and it should start working temporarily.
