The plug for the light key is probably one of the most finicky one to set. If you don’t install it perfectly aligned, the pins will bend!
There are a few posts covering that you can search in the forums. But basically, if they are bent, carefully try and realign them, and then install the cable with the light key unit outside of its housing.
https://forum.clockworkpi.com/search?context=topic&context_id=5135&q=Pins%20bent&skip_context=true