Disconnected

The door to a utility room is sealed, locked from the inside. If you can figure out how to open it, a nice reward awaits. If it appears in your dungeon, it's always in a corner of the map. You'll see a room with large windows through which you can see something purple glowing. Next to the room is the entrance, a red-lighted door that you cannot open:

Objectives
Open the sealed door.
Rewards
Rerouting Cable
Blackout Ring

Map

Walkthrough

As you stand facing this sealed, corner room, look to the wall outside the room to the right to find an open doorway. Follow it to an apparent dead end:

Note that this isn't a dead end once you destroy all of the junk piled up at its end. Clear the floor and notice a hatch leading down:

Drop through the hatch into a tight maintenance passage. Follow it to the right and continue as it curves to the left and up a short slope. At the end of the passage, look up to see another hatch:

Climb up into the room and up the ladder on the wall opposite the hatch. At the top of the ladder, turn right to see the Rerouting Cable lying on the floor:

Pick up the ring and follow the passage behind you. It almost immediately turns to the right and ends at another hatch in the floor. Don't drop down yet! Look at the bottom of the right wall just in front of the hatch to see a small opening:

If you peek through the opening, you can see why the door below isn't operating. A large power cable has been severed. You can see power in the segment closer to you, but not in the one closer to the locked door. Between the broken ends, there's a power cell. Shoot the power cell to energize momentarily the cable that leads to the locked door:

Now, drop down through the hatch and look to the right to see that the formerly-locked door is now open. Head into the room to the room to a Drzyr body, where you'll find the Blackout Ring:

That's it! Enjoy your new rings as you continue your adventures.