So I'm near University Point, near the castle, and as I'm traveling I see this strange marking on a wall that has 6 lines extending outward and a Square in the middle. I walked away as it disappeared, but as I walked toward it, it again reappeared. I thought it was some normal marking until I saw another one of these markings, this time with an X instead of a square. I'm playing on the PlayStation 4 currently, and I believe these markings are buttons. I continued and saw yet another marking also with an X. Inside a nearby building is a generator that has the option to activate it. When I tried activating it nothing happened. I believe these markings and the generator are related in some way. Can someone help me figure this out? Has this already been discovered?

They're explained in game, not an Easter Egg