Follow the path out of this dead end. Go toward the building in the back ground. Climb up to the second floor killing Geth as you go. On the second floor there is a Triangulation Tower. Use it. This helps the main force distract Saren's men.
GO back to where Shepard left the dead end then turn right. Head straight until Shepard hits a rock outcropping. Shepard can go either way around it. Take the bridge from the Geth and Krogan troopers.
While on the bridge look up and shoot the Satellite Uplink. This will also help the main force.
After the bridge, take the first right and climb the ramp to the elevated section. When at the top follow the path to the right. Take out the drones. This will help the main force.
Follow the other path out of here. When it meets another path, go right. There will be an assortment of Geth and Krogan. Kill them all. When done with the Krogan, go to the right and open the door.
Follow the path. When Shepard gets to the Security Console use it. When asked choosing "They've got enough to handle" option, will free up the main force.
Choose a door and enter the warehouse. Of course there are Geth and Krogans in there. Deal with them by killing them. Go to back side of warehouse and turn left. Follow the wall and climb stairs. In the maintenance area is a Juggernaut.
After the Juggernaut, open the door and proceed past it. Open the next door and cross bridge to another door. Open it and enter. Kill the Sarians in here. Open the elevator.
At the top will be a lab with some Krogans and some Husks. Kill them. After the fight there is only one way out of here. Open the door. Follow the path. There will be some Geth to kill. Open the door and enter. An Asarian named Rana will talk. She'll open the door to Saren's private lab.
Open the door Rana unlocked. Go through the door. Follow the path. Open the door. Open the elevator. Use it.
Exit the elevator. Follow the path. When Shepard enters the room he finds another beacon. Use it.
Back on the top level a conversation with Sovereign will begin.
Head back to the elevator. Use it. At bottom retrace route back to where Shepard met Rana. When Shepard exits her office, the bridge will drop. Cross it and kill the krogans. Follow the path to the next area.
Open the door and go down the stairs. There are two locked crates and one unlocked crate in the area. Follow the path. Along the way is a Krogan warrior, a few Geth stalkers, and some Drones. Kill them. After they're dead head up ramp. There is a crate and a locked crate up here. Use the Turret Controls.
After Shepard disables the turret, some Geth show up to fight. After the fight enter the elevator and ride it to next level.
Exit the elevator and follow the hallway. When Shepard opens the door, a few Geth will attack. After the fight, follow the path to the door and open it.
The Normandy will land. Ashley/Kaidan will set the bomb. Kaidan/Ashley will call saying they're pinned down. Shepard will have to rescue them.
Open the door near the bomb. A few Geth and Krogans will attack. Kill them. After fight follow the path to the elevator. Open it and then use it.
At the top exit elevator and head left. Take ramp up. Cut scene will show Geth troop ship. Ashley/Kaidan will call saying the bomb is under attack. Shepard has a choice of rescuing Kaidan or Ashley.
If you choose the one at the bomb, go back to elevator and use it. Exit elevator. Cross room. At big door mini radar gets jammed. Open the door. Several Geth are here, including a Juggernaut and a Prime. Kill them. After the fight Saren will start a conversation. After the chat Saren will attack. Shoot him and after so much damage he leaves.
If you choose the one at the anti-aircraft cannon. Go to the north door. Follow path. Go to AA elevator. Open it. Use it. At top several Geth will be attacking. When Shepard kills them a conversation With Saren will start. After the conversation Saren will attack. Shoot him and after so much damage he leaves.
A cut scene will show the one left behind fighting before the bomb goes off. When you are back on ship, talk to the crew and then the council. Then talk to the crew all over the ship if you like. Use the galaxy map for next mission.