The Freedom Trail questline is pretty tough, so here’s our help for you to keep running for your and your family’s survival in Fallout 4. You will have to find a location called Swan Lake on your map. There you will find a "gatekeeper" and a Behemoth called "Swan" emerging from the lake where you are close enough.
You will have to shoot at him from the distance and be sure you have a Fat Man with you (with about 4-5 mini nuke). Kill him and you will have to deal with a few enemies around.
This is the start of the trail. Talk to the tour bot in front of you to have a few more details about the trail. Now, attention to the red-brick path: you will find a marker with the A on "Trail" bracketed, remember it since this will help at the end of the trail. 7-A
Then, follow the red-brick trail leading to a building; at the bast of the steps you will find the second letter. 4-L
The next marker (2-A) sees enemies starting to come out: 3-4 feral ghouls at this location. Now the path is blocked by all the dirt, so just go down the alleyway, infested with 2-3 mongrels; 3-4 super mutants with one legendary in the building you will find at the end of the street.
Here you will find the next marker (6-O).
The next marker is near a red door you will see after jumping off a bus nearby. After you do that you will see a few enemies spawning, like 2-3 feral ghouls and some raiders (you can sneak there). 3-I
Sneak around the left street and you will find stairs cutting off the trail. Go that way and you will find a little square with 1-2 mutant dogs and 3-4 super mutants, one of them with 1 missile launcher and 3-4 rockets. Use 10mm pistols or laser weapons if you own some. The marker you will find there is at the base of the blazing fire. 5-R
Follow the trail to the back of the building, keep going to the left, then go right past the fallen billboard. You will find 2-3 super mutants and one mutant dog near the next marker. 8-D
Follow the red trailer leading to the last marker at the base of the stairs. 1-R
Enter the church now, where a feral ghoul waits for you. Outside of the entrance you just entered you will find this:
Defeat all the ghouls on this level, then find a door to the right of the “Lantern” icon from earlier. Head down the stairs into the catacombs, defeat 3-4 feral ghouls and turn left, where you will have to kill 2 more ghouls.
Here's what you should find:
The dial to the right with the cords attached will open a door, with the codes and the order you have looked at so far.
1 R (fRedoom) or (tRail)
2 A (trAil)
3 I (TRAiL)
4 L (traiL)
5 R (tRail)
6 O (freedOm)
7 A (trAil)
8 D (freeDom)
If everything's right, you'll hear the sound of the stone moving and the wall sliding back. We won't say what happens next so you can discover it on your own.