Prerequisites: Complete From Within and Outside the Wire (or betray the Institute somehow)
Trigger: Speak to Proctor Ingram
Reward: T-60 Medic Pump, 600 XP

- Once you’ve completed your circuit of the Institute and recruited Madison Li back into the Brotherhood of Steel, pay a visit to Proctor Ingram at Boston Airport. She’ll usher you into a back room where the bits of Liberty Prime, a massive robot, are strewn about. You need to help get it back into working order.

- What happens next depends on where you are in the plot:
  • So long as you’ve extracted Madison Li from the Institute, or at the very least haven’t made them into enemies yet, you’ll be asked to speak to her on Proctor Ingram’s behalf. Doctor Li is having some second thoughts, and you’ll have to talk her into helping again. She’s lingering on the Prydwen’s Main Deck, in the Power Armor repair bay. Chat with her to get her back on track. Mentioning Virgil makes this real easy.
  • If you’ve been banned from the Institute you need to get the help of Profesor Scara, a scientists in Diamond City. She’s in the Science! Center, a building just on the outskirts of the central market, down a bit of a side alley. Speak to her and she’ll move to the Prydwen for the remainder of the game, more or less.

Either way, you now have a scientist to work on the robot. Return to Boston Airport and speak to Ingram again. Prime is now out of its hiding place and ready to be assembled.

- Ingram now tasks you with finding a High-Powered Magnet. You can find one in one of the Hospitals scattered around the Commonwealth; in this case (or in my case, anyway) you’ll be directed to Milton General Hospital, to the southwest. You can also find them for sale at a few vendors - Diamond City Surplus sometimes has ‘em, for example. (You may have to go with a vendor, depending on whether or not you’ve cleared the Hospital where you’re sent already, as there may not be a Magnet sitting in the steamer trunk where it’s supposed to be located. No worries, they’re cheap.)

- Now you need to construct four Electromagnetic Actuators back at Boston Airport. Each Actuator requires the following components:
  • Five Circuitry, available by sifting through military bases and supply depots of a technological nature - most often you’ll find Circuitry while blowing up Turrets
  • One Screw, found by breaking down most weapons
  • Ten Steel, available damn near everywhere you set up settlements
  • Three Fiber Optics, usually gleaned from science equipment like Biometric Scanners and Microscopes - you’ll find this stuff in abundance if you pay a visit to the Institute’s store rooms
  • Rubber, found by breaking down a variety of common items, most often the piles of tires commonly Five found in settlements
  • One High-Powered Magnet

You can construct the Actuators in the small build spot in the north of Boston Airport. It doesn’t matter where you put them.

- Once you’ve finished the Actuators, speak to Ingram again. She needs nukes for Liberty Prime, and the only place she can think to find them is waaaay out in the Glowing Sea. First, though, you need to meet Scribe Haylen at Waypoint Echo, on the Edge of the Glowing Sea. You may run into Raiders along the way if you jump right to the Edge of the Glowing Sea, so be ready for a fight. Haylen will give you a Distress Pulser.

Sentinel Site Prescott in Fallout 4.
If it wasn't surrounded by a nuclear wasteland it might be pretty.
- Now you need to head into the Glowing Sea. Your destination is the Sentinel Site, a massive, pyramidal structure southwest of Waypoint Echo. You’ll find it easily enough if you follow the remains of the highway that stretch through the Glowing Sea. The creatures along the way are pretty nasty, and the Rads pile up quick, so… consider Power Armor. Just saying.

- The Sentinel Site (Sentinel Site Prescott, more specifically) is covered in this article. It’s a pretty straightforward area overall, and will force you into battles with a fair number of Feral Ghouls. Be ready for a scrap or two.

- Once you reach the bottommost depths of the Sentinel Site you’ll be approached by Brother Henri, a member of the Children of Atom. He will try to stop you from accessing the nukes. If you’re persuasive enough you can get Henri’s Terminal Password from him without a fight. If not you’ll have to kill Henri and destroy an Assaultron named Atom’s Wrath to get the Password, along with Henri’s Instructions. Use the Password on the terminal in this room to open up the store room with the nukes, then plant the Distress Pulser on the construction vehicle near the doors.

- BE WARNED! Something rather dire happens at this point in regards to Paladin Danse, and whether he’s currently your companion or not he will disappear for a while. If you don’t want to lose him, don’t plant the Distress Pulser. You can still get him back, but things… things get awkward.

- Return to Proctor Ingram at Boston Airport. You’ll get the honour of switching on Liberty Prime, completing the quest. This will also trigger the next quest, Blind Betrayal.