I instaled chip in the control room, but i can't find where to activate eastern power plant to power securotrons. Map marker lead to dead end.

I have the same issue but my quest is called All or Nothing. Marker just leads me to a dead end after installing the control room chip in hoover dam.

there is a breaker box on the wall that you have to flip on. It was damn hard to find for me too. Just use your local map and follow the marker.