Liberty Reprimed

Liberty Reprimed is a Brotherhood of Steel main quest in Fallout 4.

Detailed walkthrough
After the successful completion of both From Within and Outside the Wire, the Sole Survivor will be told by Elder Maxson to speak to Ingram at Boston Airport to work on a secret project. Upon meeting Ingram at the airport and she will lead them to a sealed area of the depot where the remains of Liberty Prime, the Brotherhood war machine that was destroyed by the Enclave ten years ago, is stored. She mentions the difficulty the Brotherhood has had getting it back on to its feet, and that they need the help of a scientist skilled in power systems. The next step depends on the player character's choices while they were in the Institute.

Convince Dr Li to work on Liberty Prime
If one has successfully completed From Within for Elder Maxson by convincing Madison Li to leave the Institute and work again for the Brotherhood, Ingram will let the player character know that she is reluctant to help on Liberty Prime, and ask them to convince her.

Return to the Prydwen and talk to Li. She will make it clear that she does not wish to work on Prime and "make the same mistake twice." Despite her reservations, all speech paths ultimately lead to her helping. Return to Ingram to continue the mission.

Or Find Professor Scara
If one hasn't been able to recruit Li for the Brotherhood by becoming enemies with the Institute before the quest, Ingram will tell the Sole Survivor about a scientist proficient in robotics by the name of Professor Scara, who resides in Diamond City and ask them to convince her to work for the Brotherhood. She will give the player character a piece of technology to help convince Scara.

Head for the Science! Center in Diamond City, where Scara resides. However, one will only encounter Duff, her partner. By looking at Scara's terminal (Hacker rank 3 required) or by talking to Duff about it, the Sole Survivor will discover that Scara headed for the General Atomics Galleria.

Head for the galleria, a place inhabited by non-hostile Mister Handies and Mister Gutsies. Scara is found in the Back Alley Bowling building. However, the Sole Survivor will not be allowed access to the bowling alley without turning the robots hostile if they don't pass a speech check, have an employee ID from the General Atomics factory, pay 5,000 pre-War money, or trigger the grand reopening. For more information, see the miscellaneous quest Galleria.

Once the reopening has been triggered, return to Back Alley Bowling. The Mister Handy at the counter will let the player character know that they are allowed to visit the area. In Back Alley Bowling, the Sole Survivor will find Scara. To convince her to work for the Brotherhood, the player character will need to either give her Ingram's piece of technology or pass one of three easy speech checks. Once Scara is hired, return to Ingram.

Construct electromagnetic actuators
Once the Sole Survivor returns to the airport, Li/Scara will tell them that, in order to fix Prime's arms and legs, they will need to make four electromagnetic actuators. They will then be given the electromagnetic actuators list, which lists the components required for each one. In total, they will require:


 * High-powered magnet x4
 * Screw x4
 * Fiber optics x12
 * Circuitry x20
 * Rubber x20
 * Steel x40

Fortunately, the Sole Survivor is only required to find a single high-powered magnet, as the remaining items will automatically be deposited into the workshop. The magnets are a relatively rare item but may be found in a few areas or bought from certain traders. The quest log will point towards a building containing one, usually Milton General Hospital or Medford Memorial Hospital, but visiting this location is not necessary, assuming the magnet can be found elsewhere.

Once all the required materials have been found, go to the airport workbench and craft the four actuators by placing them on the ground. Return to Ingram once the actuators are ready.

Find the nukes for Liberty Prime
Ingram will tell the Sole Survivor that Prime is still missing one of its key components: nukes to use in combat. She will inform them that Proctor Quinlan found information about a pre-War bomb storage facility located somewhere within the Glowing Sea, which holds a number of suitable Mark 28 nukes. Make preparations for the next assignment, then head for the northern part of the Glowing Sea, at Waypoint Echo, where one will meet Scribe Haylen. She will give the player character a distress pulser to use once they have found the nukes.

Head for the southeastern Glowing Sea where the Sentinel Site can be found, which holds the nukes. The area is inhabited by a large population of feral ghouls, so be prepared to fight. To access the main area, one will need to use the Sentinel Site blast door override holotape or use one of the terminals to cancel the launch order and access the facility. Head for the tunnels, where one will meet a large number of feral ghouls. At the end of the tunnel, one will see the blast door to the stockpile area. The door one can enter from is on the left, next to the broken terminal. This area is guarded by Brother Henri of the Children of Atom, who will ask the Sole Survivor the reason for their presence, stating that the area is "Atom's hallowed ground." One will need to pass a medium-difficulty Speech check to convince him to give the player character the password to the computer that unlocks access to the nukes. If the Far Harbor add-on is installed and the player character has joined the Children of Atom, they can pass an easy speech check saying they are a Child of Atom from the church in the north. Otherwise, the player character will have to eliminate him. Henri himself isn't that much of a threat, but he is accompanied by an assaultron named Atom's Wrath that will attack the player character along with Henri. Loot the password from Henri's body, then use the terminal to unlock the storage area, where the player character will need to use the pulser. If Danse is the current companion, he will tell the player character that he will stay behind to ensure the nukes reach the airport safely. If Danse is not the current companion, then his affinity drops to zero.

Return to Ingram to inform her of the mission's success.

Activate Liberty Prime
After a short discussion with Ingram and Scara/Li, the player character will be allowed to push the button to finally power up Liberty Prime. Danse's affinity will drop to zero after Liberty Prime completes all its diagnostics if it hasn't already done so. But it will restore back to its previous level after talking to Ingram. After Liberty Prime is ready, talk with Ingram and the mission completes. Ingram will give the player character a medical pump mod for T-60 Power Armor. She will then state that Maxson would like to speak with the player character, which starts the next quest, Blind Betrayal.

Bugs

 * Building electromagnetic actuators won't give credit towards 4/4 actuators built. Occasionally progress is rewarded but more often negative progress is observed (e.g. "-2/4 actuators built"). Repeatedly storing and replacing the actuators may relieve the issue.
 * Sometimes the section of gate that needs to disappear for Prime to march on the Institute remains in place after his activation, leaving him stuck in the airport courtyard aimlessly trying to find a way out.
 * When you approach Madison Li, she may not say anything except "Whatever it is, it can wait". To fix this wait 20 seconds, then she will continue with her dialogue.
 * After showing you Liberty Prime, Proctor Ingram might stay in Liberty Prime's room and refuse to speak to you again.
 * When you are told to go to Medford Memorial Hospital, the high-powered magnet won't spawn in the steamer trunk it's supposed to be in.
 * Sometimes it isn't possible to speak to Proctor Ingram in the first stage of this quest and no quest marker appears after accepting the quest. Ingram will keep talking about non-quest dialogue. Setting the quest's stage to 10/first stage may solve the problem.
 * If the player character has Spoils of War as an active quest, it is not possible to interact with Proctor Ingram to advance in this quest.
 * Apparently sometimes (triggering cause unknown) Henri is not on the right side of the very tall red blast doors... because a Rogue Institute Courser has already killed him and his assaultron... INSIDE the bomb storage room. Recommend using cheats or console commands to spawn yourself Henri's terminal password (DN166HenriPassword) to open the doors.
 * Talking to Proctor Ingram can result in dialogue for the wrong quest (mentioned in Notes above, preventing progress without becoming enemy with one of the factions). To miss out on the least content, you can use this console workaround if you want to complete Liberty Reprimed without siding with the Brotherhood and completing Mass Fusion: go to the Boston Airport where you would talk to Proctor Ingram in order to continue both quests, and type in the console to skip having to talk to her. After using the nearby workshop to build the 4 actuators and being prompted to talk to Proctor Ingram again, type  into the console to again skip having to talk to her. After meeting Scribe Halen etc. and you are again told to talk to Proctor Ingram, type, hit the red button and move away from her. She will initiate the same unwanted Mass Fusion quest dialogue if you're close to her, so keep a distance as Liberty Prime is booting up. Finally you will be asked to talk to Proctor Ingram one more time, which you still can't safely do, so type  and finally you're finished.