Location of the door:

Head to the red lit small space and jump down:

Continue until you find this grate, smash it and go through:

When inside, hack this computer to unlock the door:

Location of the door:

Smash this grate:

Continue forward and jump through the opening at the end:

When inside, hack the computer to unlock the room:

Location of the door:

Bullet jump to this grate, smash it and go through:

When inside, hack the computer to unlock the door:

The room looks like this. There is a computer nearby and a yellow door at the far end:

On each side of the room, there is a reactive crystal beneath:
Switch to Operator and shoot the crystals with your amp, then go back and hack the computer.
The door will open in approximately 10 seconds.