I have tried to find the key for the SHD cache about 3 times now. I understand that you go through the underground go through some doors, shoot a switch through a door window and the door pops open and you move on. Then around the corner is a heavy that is supposed to have the key from the videos I have watched, but once he is killed no key.
Any advice? It is in Warlords of New York Civic Center. Incase you were curious as to what location I am referring to.