"Find restraining bolt" is a mission objective in the story mission "Infinite Loop" in Borderlands: The Pre-Sequel
Walkthrough[edit]
Time to get a Restraining Bolt and shut down one of these two CL4P-TP units. Turn to the North and head for Robotics Durability and Adaptability Research by the Stalker Biome.
Head to the North when you reach the room between the two. There are a lot of Needle Stalkers to deal with as you make your way North.
In the room just before Aquatic Life Stabilization, as you enter it, look to the East. You will see a console you can interact with. Do so to get access to what you're looking for.