In the room with the generator that you had to crouch to get into, kill the enemies. Over the other side is a console showing a map of the base. Press the 2 buttons to light up parts of it. To the left of the console is a wall display showing the blue code. Look at it and it will be stored in your datapad. You will need it later. Now leave the room via the shielded door (there is a button to remove the shield), go up the stairs and follow it round to the left.