There will be a few guards and Enforcers here so blast them all to pieces. Pick up the health and ammo and take a left behind the stairs and follow this around. You will see an odd-looking yellow light on the ceiling right behind the elevator so shoot it to activate the last secret of this level. Crouch down to snag the health and grenade and head to the front again (from either side - it doesn’t matter). Go up the stairs and around the left to the clearing. There’s some ammo at the end but look for the elevator. Enter the elevator to finish level 1.