House of Reconing easter egg hunt(possibly

So i am doing laso and on House of Reconing. In the second main area, i went to the very top of the tall center building. I found a switch just like the switch towards the beginign if the game. I found a second one in the same room. I cant find a third(yet as im trying to while fighting)

I figured i should bring this up, also i was listening to youtube when i hit them so i had no audio from the game and i have already triggered a checkpoint(honestly being thebmost annoying part about laso xD) and dontkniw if there was some audio que unfortunately bit i wanted to bring this up so we can possibly find out what it is.

There are 3 buttons in total on that level. When you press them all a rocket warthog drops.

Ooh. I hadn’t seen that one so was unsure

Where’s the 3rd button?

Inside one of the rooms where the holograms talks to you.