As Shepard goes down the ramp the mini-map gets jammed. Hmmm I wonder, what could that mean? I guess it means a fight with Shock Troopers. Keep following the walkway until Shepard finds the elevator. Take it down.
On the next level Shepard fights some drones. Take the next elevator down. It will short out near the bottom. Jump out and keep dropping until you find Liara.
After the conversation, head down the ramps. More Geth show up. Go west to the supply tents. Look for 2 lockers. Use the Mining Laser Control to blast a hole in the wall.
Head down in the hole. Go to the end and use the device to ride the elevator up. Go to Liara and she'll be freed.
The laser will make the ruins start collapsing. At the end of the elevator ride will be a cut scene and then a battle with a Krogan Battlemaster.
When you kill him another cut scene kicks in of the party escaping the ruins destruction. Shepard will be on the Normandy talking to Liara and the rest of the party.
Liara can join the party during the conversation.
After all are dismissed Joker asks if Shepard wants to talk to the council. When Shepard is free to roam, talk to party members in various locations in the ship. When Shepard is done go to the Galaxy Map and choose the next Destination.