The Borg have done something to the Coolant tanks of the plant. Defeat the two drones surrounding the tanks to gain access to them. Interact with the tank to seal it off. It takes 2 minutes for the Borg to beam back in and start another coolant leak. The coolant tanks are located mainly at the corners of the corridor and at the ends. 10 Coolant leaks must be sealed to complete this mission.
The Borg are attempting to divert the power generated by the plant to their Probe. Stop them by cutting off their access at each of the Control stations. You have to interact with two consoles at each station. The consoles are guarded by numerous Borg drones. When you interact with one of the consoles, two Borg drones will beam in behind you to stop you. Defeat the drones if they interrupt you to successfully interact. If you're in a team, have one person interact with the console while the others cover them.
Engineers have trapped themselves behind forcefields to keep out the encroaching Tactical Drones attempting to assimilate them. Clear the area and get the Engineers out from the forcefields. There are four chambers with engineers, each in the outer areas of the map. Go through the side doors of the the alcove chambers to reach these chambers. There will be three Tactical Drones who are guarding the Engineer. After they've been defeated, signal the Engineer to lower the force field. 15 Engineers must be rescued to complete this mission.
The Borg have established alcoves in the lower levels of the Power Plant. They're leeching power from the plant to regenerate their drones. To deactivate the alcoves, you'll need node keys which the regenerating Borg drop. You need a total of 5 node keys to shut off 1 alcove group. Have one person collect the node keys so that they can shut off the alcove group. 10 Alcoves must be deactivated to complete this mission.
The objective here is to hold off the Borg who have made this area their base. You'll have to beat down the Elite Tactical that comes out of the main Forcefield, then defeat the surrounding Drones. After defeating the Drones, Heavy Tactical drones will appear. After the Heavy Tactical drones are defeated, the Elite will make one last stand. After defeating the Elite, take the loot bag that drops behind the console that triggers the mission to claim the Power Plant Access Codes. These codes are what you use to turn the mission in.