In Call Of the Dead, Paradise Help...?

Ok so me and some friends were trying to find out how to get to paradise, and on round 4 we got a crawler and turned on the power then went back to the starting area and cleared the other boat out to get to the light house. When you go all the way down stairs (behind the first box near the lighthouse) and go near a certain door, You can here the characters from Kino/Ascension on th other side yelling/talking to each other and yelling "IS ANYONE OUT THERE?, OPEN UP!" - so apparently you have to listen to their full convo and then your supposed to hit a switch that appears 1 floor up on a table ( this info was from my friend who looked it up but i cant find this info anywhere ) - anyways we couldnt find this alleged switch so instead on the spiral staircase (in the light house) there are these combination locks that make a sound like they belong to a heater or something - each lock has a different color from bottom to top - 1st floor (Dark Blue) - 2nd Floor (Blue) - 3rd Floor (Orange) - 4th Floor (Yellow) - so thats why i thought that it something to do with the heat also the 1st floor is made out of ice and has more spiral staircase under it so i thought it could melt or something - so we turned them all up to 9 to see if it would melt - we wait 2 mins - nothing, so then we try 1941 from top to bottom then bottom to top - that didnt work either but my friend went back to the door after that and shot it and they started talking again - apparently my friend looked it up again and said that everytime you change a number a number above it (or below it) changes by itself so there needs to be 4 people (1 at each combination switch) - We had 3 -_- // anyways the point is i guess to get the Stand-In and Ensemble Cast you need to open that door and meet up with Dempsey, Richtofen, Takeo, and Nikolai and i guess there might be a cutscene or you just find them - but i dont get it - for Stand-In it says you can get it in Solo or Co-op and then Ensemble Cast says Co-op - so there has to be a way to get there in solo - if you actually read all of this and you find ANY info at all about this please put it in your answer below.