Now that you are allied with Father the Institute you must clear all the Enemies and help the Institute govern their cause. This is the Final Part of the Institute's Essential Quest where you will eliminate the Leaders of Different Factions like The Railroad and Brotherhood of Steel. In This Institute Quest Walkthrough, we will complete the last three quest: End of the Line, Airship Down, and Nuclear Family.
After the Reactor is activated and you have agreed to join the Institute, it's time to defeat the other faction leaders, starting with the Railroad leaders.
Objective
Walkthrough
Go and Speak with Father and he will ask you to take the Railroad and their leaders down. You can locate them at the Old North Church in Boston, you can use your Pip-Boy to fast travel or if any doubt with the quest. Once you get inside the secret opening of the church you must start eliminating all the leaders of the Railroad One by one.
There are 6 leaders of Railroad in total: Desdemona, Drummer Boy, Glory, Tinker Tom, Deacon and Doctor Carrington. Mind you this is a very tough battle so go prepared and if you find trouble taking these enemies down then make use of the traps in the hall or try using the Power Armor while some nukes on the ground. Go and have a word with Father once you are done dealing with the Railroad leaders. This will complete the mission.
The railroad is Down and now we should focus on the Brotherhood of Steel and take then down along with their Robot before you destroy all the generators.
Objective
Walkthrough
As you are back to the Institute after defeating the Railroad enemies, you see the Brotherhood of Steel has been set as your next target. First speak to Doctor Li or Evan Watson inside the Advanced Systems where Doctor Rosalind Orman will inform you about the plan and also provide you with Institute Beacons used to spawn Synth to aid you.
Directly leave the Institute and fast travel to Boston Airport to infiltrate the terminal. Then try to make this mission as stealthy as possible as there are hell lot to take down ahead. If you think you are not prepared just escape the mission. You need to destroy all three Brotherhood of Steel's Generator. Make use of the Map whenever possible.
The Generator's locations:
Once you deal with all the generator a Synth will appear at the Top of the liberty Prime and it will start the reprogramming. All you need to do is defend the Synth from the Enemies until it finishes the reprogramming. After Defending successfully, you need to escape the area towards the North and make sure you have a look at the Explosion. Thus ending the Mission to an end and start of the Final Essential Mission of the Institute.
The end to the all the Essential Quest of The Institute after eliminating the Railroad and Brotherhood of Steel and let Institute rule in the Outside world.
Objective
Walkthrough
Now that the Brotherhood of Steel is gone you need to head back to the Institute and speak to Father and inform him about your progress with the Mission. Father will conclude the Essential Quest and Thus leaving you with other Miscellaneous and Radiant quests.