Here is a complete walkthrough on how to access the locked Junction Box in Tapping the Grid mission of Starfield.
Starfield has been able to live up to its hype before the launch, being the largest Bethesda project ever. Starfield features a long list of challenging and easy missions that send the players to different parts of the solar system and task them with completing certain objectives. Each mission in Starfield comes with a unique task of its own. While some of these tasks can be completed without any hassle, others would definitely give the players a tough time.
During the Tapping the Grid mission in Starfield, you will help Louisa Reyez investigate a potential power cut in The Well. As a part of this mission, you will be tasked with finding certain Junction Boxes and deactivating each of them. Most of the Junction Boxes can be found very easily just by following the quest marker. However, the last Junction Box would require you to solve a challenging puzzle before accessing it.
How to Access the Locked Junction Box in Starfield
After meeting with Louisa at the start of the mission, she will brief you on the mission objectives. You will be tasked with finding four Junction Boxes in total. The first, second, and third Junction boxes can be found near each other around the area of the quest. However, Louisa will tell you that the last Junction Box is hidden behind a locked door, and she has forgotten how to get past it.
After you are done finding all the other Junction Boxes, head upstairs and go to the Trade Commission. After you get inside the room, you will find four junction boxes in front of you with four green lights in the background. You will find a locked yellow door on the right side of the boxes. Find the main junction box behind this door, which is required to be deactivated to complete this quest of the mission. Here, you have to light up all four green lights on the screen behind these switches in order to open the door.
In order to open the locked door, you will need to divert the power to this door by deactivating the four Junction Boxes in front of you. The solution to this puzzle is very simple. Start with the Junction Box on the left side. Deactivate the first switch and move to the next one. Keep repeating the same process until you reach the fourth Junction Box. After interacting with all the boxes, you will notice that the yellow locked door has already opened, giving you access to the main Junction Box.