Hit the marker outside some modest law offices to begin.
Grab Joule's eyecatching (and/or eyewatering) car and make for the TTX.
Reach the plaza, and clear out troops.
Having stopped their hack, it's time to execute one of your own. Once it begins, you have to defend the console from all comers. Don't be afraid to continually reposition your turret- bot to get a better angle of fire, and to distract LEGION troopers that are crowding you too much.
When the hack completes, your next task is to destroy three outlying antennae. Leave your turret back in the central plaza, and zap these targets yourself. You can get a little extra range by using Fine Aim.
You'll then face one last massive enemy push- an ideal time to deploy your MAYHEM move.
Mop up the survivors and hack the console one last time to overload it- destroying the machine and ending the mission.