Garza will tell you of some 'dead good guys' and you'll find them underneath the corrugated iron shanty town. Move on and you'll find an ISA soldier who is still alive, but not for long. It's an ambush from above! Take cover and kill the Helghast and try and get as close to the machine gun nest that will begin to open up on your position.
Kill the Helghast, then take control of their gun and you will be ready to blast enemy troopers that will come from an enemy gunship with zero danger of personal pain. Blast them as they rappel down and kill the other Helghast in the areas. Once they are dead follow life-loving Garza and let him give you a boost up to a platform. Follow the waypoint and this time use a grenade to get rid of the explosives and laser tripwires.
You'll see Garza trying to get through to the rest of Alpha. Turn 180 degress around so you face the fascistic Helghast building with the red drapes and you will see another Helghast Symbol. Follw the waypoint and kill all the Helghast while you run for the substation's door.
Rig it with a charge, set it off and enter. You'll now face a simple set of Helghast, but your main task is to set four charges onto the substation's supports. Rig them all and run out of the substation. You don't have to kill any remaining Helghast since once you are outside you'll blow the charges and destroy the entire building.
[Look out for part 2 of this guide tomorrow