How to unlock: The quest will start automatically near the Museum of Freedom (M1,2) after completing the Out of Time main quest.
- Enter the museum
- (Optional) Take the laser musket
- Find the imprisoned settlers
- Talk to Preston Garvey
- Obtain fusion core
- Install the fusion core in the power armor
- Put the power armor on
- Take the rotating turret
- Clean Concord of all enemies
- Go to Preston
- Join Preston Garvey in Sanctuary
Securing the museum
The quest begins near the Museum of Freedom in the town of Concord. Look around in front of the museum to find a very good short laser musket. Pick it up to complete an optional quest objective (collect ammo for this gun from a nearby Minuteman corpse) and then enter the museum via the main door.
Start exploring the main floor of the museum - you can open a gate which has an advanced lock (Locksmith perk and a bobby pin required) or you can go around through the rooms to the right. Be prepared to defeat new raiders. Some of them will be on this floor and some them will be on the upper floor (it's recommended to keep using the rifle you've collected not long ago).
Head up and continue eliminating all the new raiders you encounter. You can't get lost, because there's only one path leading to the room where the settlers have barricaded themselves. Talk to Preston Garvey and then to Sturges when you get there. You'll find out about an inactive power armor on the museum's roof which you'll be able to use to deal with the remaining raiders.
Important - There's a bobblehead in the room with the settlers. Pick it up to get a permanent increase to Perception.
Finding a fusion core
Go back the same way you came and stop near a destroyed part of the floor. Jump down to reach the basement area and find a locked gate. There's a computer terminal next to it and you must interact with it. Solve a simple mini-game in order to open the gate, enter a small room and collect the fusion core.
Alternative solution: If you have at least one bobby pin in your inventory and you don't want to hack the terminal you can try working on the lock on the gate. Save your game before you do that, because you can lose your bobby pins if you fail to open the lock.
Activating and using the power armor
Return to the room with the Minutemen and proceed to the door on your left in order to continue your exploration of the museum. Use the door to reach the museum's roof and approach an inactive T-45 power armor in order to place the fusion core inside it. Enter the power armor and go to the crashed vertibird so that you can pick up a vertibird minigun. Get to the edge of the roof, jump down and start attacking new raiders led by Gristle using the newly acquired minigun.
Things will get complicated soon, because a deathclaw will come out of the ground near one of the street junctions. As soon as this has happened ignore the remaining raiders and focus your efforts on attacking the deathclaw. Keep firing without any interruptions and prevent the monster from getting too close, because you can quickly die even when you're hiding inside a power armor.
Move back when you'll have to reload the minigun and then resume the attacks. You can use other weaponry to weaken the deathclaw (and also blow up nearby cars), but the minigun should be enough to kill the monster. Deal with the raiders left alive so that this battle can finally end.
Finishing the quest
Exit the power armor and then enter the Museum of Freedom again. Talk to Preston Garvey and to Mama Murphy in the main room to find out that the Minutemen will head back to Sanctuary (you'll also receive fusion cells and bottlecaps). You will unlock a new main quest (Jewel of the Commonwealth). If you don't mind continuing the cooperation with Minutemen faction, you can first complete this quest. Use fast travel or return to Sanctuary on foot along with the Minutemen. Once the new allies are all in Sanctuary find Preston Garvey and talk to him again. You will be asked to provide help in rebuilding in the settlement (major quest Sanctuary) and in assisting another group of settlers (minor quest The First Step). They are going to be the first ones out of many side quests you will be able to perform for the Minutemen faction (there are also other factions in the wastelands).
If you plan to cooperate with one of three remaining factions (Brotherhood of Steel, Railroad or Institute), you can stop completing this quest once you unlock the Jewel of the Commonwealth main quest.
Quest rewards: Experience points, new main quest (Jewel of the Commonwealth), new Minutemen quest (Sanctuary), new Minutemen quest (The First Step).