Operation Ticonderoga

Operation Ticonderoga is a Railroad side quest in Fallout 4.

Detailed walkthrough
Upon entering the Railroad HQ, the Sole Survivor will be approached by Drummer Boy and notified that Desdemona wishes to speak to them. During the conversation with Desdemona, the Sole Survivor will be told to check on the status of the Ticonderoga Safehouse and kill any Coursers that get in their way.

At the safehouse, there will be multiple synths as well as a Courser named X9-27, who will approach the Sole Survivor. During dialogue there will be two persuasion options, one option asking why the Courser is there, and a more difficult one stating that the Sole Survivor is from the Synth Retention Bureau. Passing will prompt the Courser to tell the Sole Survivor to leave via the stairs as the elevator is now disabled, however, the two turrets on the way to the terminal that controls the exit door, as well as the turret at the exterior lower level will have the player listed as an enemy, and if they so much as detect the player, will turn the synths and Coursers hostile.

Upon attacking the Courser, all synths will become hostile towards the Sole Survivor. When all enemies have been dispatched, head towards the elevator a few levels below. When the Sole Survivor reaches the ground floor and leaves the building, they will be attacked outside by another Courser who is accompanied by a few synths. Once they are dealt with, head back to Desdemona and notify her that all Railroad agents are dead. This will complete the quest.

Bugs

 * If the stair exit was previously unlocked, the Sole Survivor can enter through the stairs and begin in the very ground floor of the suite. The Courser will start moving toward them to initiate dialogue. The elevator from the exterior ground floor will still be usable but the elevator inside the suite will not be functional.
 * When entering Ticonderoga interior cell, Courser dialogue starts automatically. By not talking to him, the game will not allow you to progress even after all targets are dead. This can be fixed by entering the following in console: . (Use of will prevent the quest from ending prematurely. Stage 210 will update the quest properly and enable the Courser outside Ticonderoga.) Alternatively, use the command . This resurrects the Courser, who will attempt to initiate the mandatory dialogue.
 * If you quickly activate the elevator to head back down, the elevator will stop functioning and lock you out of the building and stop you from being able to complete the quest.
 * Resolving the dialogue with the Courser peacefully causes all the NPCs in the area to be non-hostile except for the machine gun turrets which will shoot on sight and cause all the NPCs to become hostile. It is possible to either stealth past all three turrets (including one at the entrance by the second Courser), to stealth destroy them and wait out any Caution, then the synths and Courser will be friendly, or just teleport to the Institute and avoid them all completely.
 * Once starting this quest, the game can crash to desktop when in close proximity outside the building.
 * When arriving at the Ticonderoga house the quest will get stuck because there is no one there, and the elevator cannot be used. This can be solved by teleporting the Sole Survivor to the location of X9-27 by entering the console command.