I have 3 chargers. Two went bad after 4 years.
There's no diagnostics that are performed by Specialized in this situation and the charger can not be fixed, Specialized policy. So I'll be buying another one.
I would suggest that Specialized look into this charger's reliability, a method of diagnosing any problem, the idea of placing LED's on the outside of the charger for the user to determine its status and a longer warranty.