Once you reach Seattle you have to open a huge gate. This How To Open The Main Gate In The Last Of Us Part 2 guide will tell you the steps you must complete before you’re able to open the gate to let Dina and Shimmer into the town through the main gate.
Once you have climbed over the main gate you have to find a way of powering the main generator so you can open the Main Gate. The first part is very basic, power up the generator and attach it to the gate mechanism so you can open the smaller gate to gain access to the area with the bigger gate. Make sure, in the building directly next to the generator, that you open the drawers inside so you can find the code to the Main Gate, you will need that later.
How To Open The Main Gate In The Last Of Us Part 2
On the other side of the smaller gate, just to the left as you enter, there is another generator. You will need to power up this generator first. Approach the gate mechanism that you powered previously and take the yellow cable out of the box. You cannot wait it around to the 2nd generator as the line is too short. Instead you must throw it over the fence. Hold L2 to aim and use R2 to throw the yellow wire over the fence towards the second generator.
Once the second generator is powered head into the nearby building and activate the switch that says “Main Gate”. You will need to put in a code, which you found on the documentation in the first building. The code to open the Main Gate is 0512. Simply enter the code and you can open the Main Gate and progress with the story alongside Dina and Shimmer.