The two doors near eachother that you can't open are tied to a quest - if you agree to take a test for one of the guys hanging out near there he opens the doors. If he is too dead, or hostile, for that to work, you will never get in (none of the quests you miss out on by fighting all the soldiers is critical to the game or gives any specially nice items).
The door with the four wires must be opened by using the four levers you already used - they must be pulled in the correct order to make a four word sentence.