Find the terminals in the reactor's auxiliary system and cycle their power.
- Turn to the marker and head across the Rig
- Inside this covered section, you will encounter a number of Fallen: Marauders are guarding the location.
- Once inside the far portion, go forward and take the stairs upward.
- There are 2 Marauders guarding a terminal in the upper level.
- Nearby the ledge you will find a terminal to interact with.
- Do so to trigger the first of the two consoles.
- Make your way over toward the Solarium.
- You will find the marker leads toward an opening
- Go into the opening where you will find a number of Shanks.
- Fight through the shanks and interact with the marked terminal.
- With the second terminal activated, the methane reactor will start coming online.