TL;DR

The Lock Device Switch objective is part of the Gate to the Otherworld main quest in Chapter 4 at the Scholastone Institute.
After Octavius finishes his speech, head to the northeast corner of the round plaza and follow the lantern-lit path underground.
Interact with the wall panel hatch at the bottom to start the button puzzle.
Press the buttons in this order: Top-Left → Bottom-Right → Bottom-Left → Top-Right → Center. All buttons glow when the puzzle is solved.
Back out to reset the puzzle if you make a mistake — there is no penalty.
After solving it, interact with the same panel again to pull the handle.
Return upstairs and use Axiom Force + Force Palm to insert all four cube-shaped batteries into their pillars.
Use Axiom Force to extract the unstable core, which summons the boss Tenebrum.
Beat Tenebrum by using Blinding Flash to reveal its weak point, then hit it with Force Palm mid-air three times.
Rewards: 1 Abyss Artifact and the Key to the Spire of the Stars.

The Lock Device Switch in Crimson Desert is one of the most searched objectives in the game because the entrance to the underground chamber is not obvious and the button puzzle gives no instructions. This guide walks through the full Gate to the Otherworld quest — from finding the hatch underground to inserting the batteries, pulling the core, and defeating Tenebrum. For more on the quest chain this belongs to, check our guide on the Gate to the Otherworld full walkthrough and our Crimson Desert guide hub.

Table of Contents

Quest Context — Gate to the Otherworld

This objective appears during Gate to the Otherworld, the 56th main quest in Crimson Desert and a key part of Chapter 4: The Price of Knowledge, Sub-Chapter: Forbidden Knowledge. It takes place at the Scholastone Institute in the Hernand Highlands region, immediately after the quest On the Right Path.

You arrive at Scholastone and listen to Octavius, an orc scholar, give a speech about his experiment to open a portal to the Abyss. Once the speech ends, the lock device objective becomes active. The quest has four phases in total: the underground lock device puzzle, inserting four batteries into pillars, extracting an unstable core, and fighting the boss Tenebrum.

How to Find the Lock Device Switch Underground

After Octavius finishes speaking (about 30 seconds of dialogue), your minimap will show the objective marker pointing below you underground. Many players get confused here because the entrance is not directly in front of the device — it is around the corner.

Here is exactly how to get there:

From the round plaza where Octavius was lecturing, face northeast.
Look for a path lined with hanging lanterns leading into the rock face — follow it. The lanterns make it easy to spot.
The path leads down a staircase into the lower underground chamber.
At the bottom, turn toward the back wall. You will see a large wall panel covered in symbols — this is the lock device hatch.
Interact with the panel to begin the puzzle.

How to Solve the Lock Device Switch Puzzle

The wall panel shows a 3×3 grid of 9 buttons. You need to press the correct buttons to make all of them light up and unlock the device. The puzzle has no time limit, so take your time.

Use the D-Pad Left/Right to cycle between which button you are about to press. This is the easiest way to select the exact button you want without trying to aim manually.

Quick Solution — Press These Buttons in Order

The confirmed working solution is:

Top-Left
Bottom-Right
Bottom-Left
Top-Right
Center (Middle)

This follows a diagonal corner pattern — the four corners first in an X shape, then the center button last. When all buttons glow, the puzzle is solved.

Alternative solution that also works: Middle → Top-Left → Bottom-Right → Top-Right → Bottom-Left.

Made a mistake? Back out of the interaction screen entirely to reset the puzzle, then start again from Step 1. There is no penalty for resetting. The puzzle state persists within your current session but resets if you reload a save.

After Solving the Puzzle

Once all buttons are glowing, interact with the same wall panel again to pull the handle. A cutscene plays showing the underground machine boot up and the ceiling mechanism above the plaza activating. Head back upstairs using the staircase to the left of the open pillared section.

How to Insert the Batteries

Back on the surface in the round plaza, you will find four cube-shaped batteries floating in the air near four pillars, crackling with electricity. Each battery belongs to the pillar directly in front of it — check your minimap for the four orange objective markers to identify each pair.

Here is how to insert each battery:

Hold Axiom Force to grab a floating cube and lift it.
Move the cube so the side with four lights faces you — the cube needs to be correctly oriented before insertion.
Float the cube directly in front of the slot opening on its pillar. The cube will auto-align and rotate into place when it gets close enough.
Release Axiom Force, then immediately use Force Palm to punch the cube into the slot. Axiom Force alone does not complete the insertion — the Force Palm strike is required.
Each successful insertion fires a laser beam toward the central orb. Repeat for all four batteries.

Once all four batteries are installed, a cutscene plays and Octavius begins the experiment. Things do not go as planned. For more on using Force Palm and Axiom Force effectively, check our guide on how to use Axiom Force and how to use Focused Force Palm.

How to Extract the Unstable Core

After the cutscene, the portal becomes unstable and a new objective appears: remove the unstable core. Here is how:

Aim at the glowing blue orb in the center of the device using Axiom Force.
Hold Axiom Force and simultaneously push the Right Stick upward for several seconds.
The core will tear free from its housing.

Octavius gets pulled into his own experiment. A shadowy entity called Tenebrum emerges from the rift and the boss fight begins.

How to Beat Tenebrum

Tenebrum is a uniquely designed aerial boss fight — it uses completely different mechanics from any previous encounter in the game. This is more of a movement puzzle than a standard combat encounter. You fight entirely in mid-air.

Step 1 — Reveal the Weak Point with Blinding Flash

Before attacking, you need to reveal Tenebrum’s weak spot:

Hold L1 + R1 (PS5) / LB + RB (Xbox) / CTRL + Left Click (PC) to enter Blinding Flash stance.
Aim at Tenebrum and activate it. A square marker will appear on the creature’s body.
You only need to do this once — the game gives a tutorial prompt for this and the weak point marker stays visible for the rest of the fight.

For more on Blinding Flash and its uses, see our guide on how to use Blinding Flash in Crimson Desert.

Step 2 — Take to the Air

Tenebrum circles the open section of the plaza where the floor has collapsed. To reach it, you must get airborne:

Move to the center of the plaza where the floor section is missing.
Double-press the jump button to activate your wings. The updraft in this area will carry you upward naturally — you do not need to jump from pillars.
Use the wind currents scattered across the arena floor to regain altitude if you start to fall.

Step 3 — Hit it with Force Palm

Once airborne, the fight pattern is straightforward:

Tenebrum moves constantly and fires black shadow projectiles at you. These track and hit hard — dodge them or use the pillars as cover.
Wait for Tenebrum to drift to the center of the arena and begin charging a shockwave attack. That is your window.
While in the air near it, use Force Palm to strike the exposed weak point.
One clean hit deals significant damage. Repeat three times total to finish the fight.

If your Spirit depletes mid-fight: duck behind one of the pillars and hold both sticks to meditate and recover Spirit before going back up. If you fall to the lower level, you respawn upstairs and any damage already dealt to Tenebrum remains — the fight continues where it left off.

Gate to the Otherworld Rewards

After Tenebrum is defeated:

Pick up the Abyss Artifact that spawns at Octavius’s last position in the plaza.
You also receive a Key to the Spire of the Stars — your next destination in the Forbidden Knowledge arc.

To use your Abyss Artifact reward, check our guide on how to open sealed Abyss Artifacts in Crimson Desert. For the quest that follows, our Spire of the Stars puzzle solution covers the next challenge in full. To beat Tenebrum in a rematch later, use the Boss Rematch system once you have unlocked it in Patch 1.05.00.

Common Issues and Fixes

I cannot find the entrance to the underground chamber. Go to the northeast corner of the round plaza and look for the lantern-lined path leading into the rock face. Do not loop around the dome — the lantern path is the direct and fastest route down.

The puzzle buttons are not all lighting up. You are pressing the wrong buttons or in the wrong order. Back out entirely to reset the puzzle and start again with Top-Left → Bottom-Right → Bottom-Left → Top-Right → Center.

The batteries won’t go into the pillars. Axiom Force alone is not enough. You need to release Axiom Force once the cube is in position, then immediately use Force Palm to punch it in. Make sure the four-light side of the cube is oriented toward you before releasing.

I cannot pull the unstable core out. Hold Axiom Force aimed at the blue orb and simultaneously push the Right Stick upward. Hold both for several seconds — it takes a moment before the core tears free.

Tenebrum is moving too fast to hit. Do not chase it across the arena. Wait at the center in the air and let it come to you during its charging attack. That is the only reliable hit window. Use wind currents rather than jumping to maintain altitude.

Related Guides

Crimson Desert is available on the official Pearl Abyss site, Steam, PlayStation Store, Xbox, and the Epic Games Store.

How to Activate the Lock Device Switch in Crimson Desert

Quest Context — Gate to the Otherworld

How to Find the Lock Device Switch Underground

How to Solve the Lock Device Switch Puzzle