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, you will be told by Elder Maxson to speak to Ingram down at the Boston Airport to work on a secret project. Meet Ingram at the airport and she will lead you to a sealed area of the depot where are stored the remains of Liberty Prime, the Brotherhood war machine that was destroyed by the Enclave ten years ago. She mentions the difficulty the Brotherhood has to get it back onto its feet, and that they need the help of a scientist skilled in power systems.

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

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

Head for the Science! Center in Diamond City, where Scara resides. However, you will only encounter Duff, her partner. By looking at Scara's terminal (Hacker perk level 3 required) or by talking to Duff about it, you 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. However, you will not be allowed access to the bowling without turning the robots hostile if you don't trigger the Grand Re-Opening.

To trigger the re-opening, go up the Director's office. When you go up to the Director's office you will have several options to interact with him, they will all end in the Director demanding that you identify yourself.

Several options involve passing speech checks. It is also possible to acquire a General Atomics ID card from the General Atomics factory which will allow you to identify yourself without a speech check. If you succeed any of the speech checks or present the ID, you can reopen the galleria and get the grand prize for the reopening raffle. If you do attempt a speech check (difficulty not dependent on Charisma), and fail, the Director will become hostile along with all the other robots at the facility.

Alternatively, if 'The Director' has been destroyed you can use a password saved in the supervisor's terminal to access the computer in the Director's office, however the terminal's functions are disabled as long as 'The Director' is still functional. The terminal will provide you with the options to start the Grand Reopening, Shutdown all robots or initiate a self-destruct sequence in all of the robots. Updating the Director's computer's firmware (re-opening the galleria) will immediately end the hostility of all the remaining Mr. Handies.

Once the re-opening has been triggered, return to the Back Alley Bowling. The Mister Handy at the counter will let you know that you are allowed to visit the area. In the back alley, you will find Scara. To convince her to work for the Brotherhood, you 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 you return to the airport, Li/Scara will tell you that in order to fix Prime's arms and legs you will need to make electromagnetic actuators. For that, you will need to find high-powered magnets. They are a relatively rare item, but may be found in a few areas or bought from certain traders. Your quest log will point you towards a building (usually the Milton General Hospital) to find the magnets required for the work. Building the four actuators require: To help you gather the materials, Ingram will tell you to search around the airport depot for scrap materials. Once you have found all required materials, go to the airport workbench and craft the four actuators by placing them on the ground. Return to Ingram once the actuators are ready.
 * High-powered magnet x4
 * Screw x4
 * Steel x40
 * Fiber optics x12
 * Rubber x20
 * Circuitry x20

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

Head for the south-eastern Glowing Sea where you will find the Sentinel site, 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, you 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 you will meet a large number of ghouls. At the end of the tunnel, you will see the blast door to the stockpile area. This area is guarded by Brother Henri of the Church of the Children of Atom, who will ask you the reason of your presence, stating that the area is "Atom's hallowed ground". You will need to pass a medium-difficulty speech check to convince him to give you the password to the computer than unlocks access to the nukes. Otherwise, you 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 along with Henri. Loot Henri's body of the password, then use the terminal to unlock the storage area, where you need to use the pulser. If Danse is your current companion, he will tell you that he will stay behind to ensure the nukes reach the airport safely.

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

Activate Liberty Prime
After a short discussion with Ingram and Scara/Li, you will be allowed to push the button to finally power up Liberty Prime. After doing so, talk with Ingram and the mission completes. Ingram will give a medical pump module for a T-60 armor. She will then tell you that Maxson would like to speak with you, which starts the next quest, Blind Betrayal.

Bugs

 * Sometimes the section of gate that needs to dissappear 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, and 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.