Ad Victoriam Main Story, Brotherhood of Steel Quest

1. Speak to Proctor Ingram

In order to get Liberty Prime's running under his own power, I should speak to Proctor Ingram.

2. Plug In Beryllium Agitator

Plug the Beryllium Agitator into Liberty Prime's reactor port.

3. Activate Power Transfer Switch

With the Beryllium Agitator firmly in place, all that remains is pressing the Power Transfer Switch which should start up Liberty Prime's reactor.

4. Follow Liberty Prime

It's time to take the fight to the Institute. I should escort Liberty Prime to the ruins of the C.I.T.

Follow him or use Fast Travel to C.I.T. Ruins.

5. Defend Liberty Prime

I've reached the ruins of the C.I.T. I should defend Liberty Prime as he smashes his way into the Institute's underground facility.

6. Enter the Institute

Liberty Prime has successfully penetrated the Institute's defences. I should enter the Institute and begin the final phase of the attack.

7. Quest completed

The final attack on the Institute has begun.

Next / new quest is The Nuclear Option (Main Story, Brotherhood of Steel).