Original_Sin wrote From my understanding, the Fog Horn input order is different each time you do the Easter Egg, so you have to listen carefully to what order it gives you as soon as you do the steps with the Levers and Wheel in the boat.

Fog horns are the same everytime, if you are not hearing a bleeping noise when you activated a radio, then you need to go knife the door which richtofen and co are behind, then re-do the radios until you see a flashing star in the sky and the submarine has submerged, then you can start with the fog horns