Just throwing out a random thought with zero evidence, as are the rest of everyone as well.
I think he successfully accomplished the approach but failed to go visual, at night, with wx likely below appch mins, and this is a simple loss of control. It’s not unlikely he had minimal aircraft lighting turned on with the fog conditions, and may have not had a lit up appch lighting system or may not have keyed airport lights during his high workload, and simply failed to transition to visual flight.