This side-mission can be found by entering the Normandy’s galaxy map and having the ship travel to the following location:
Caleston Rift > Talava > Taitus.
Scan the planet and locate the anomoly to begin the mission.
Once you land, pick up the nearby power cell and then hack the disabled heavy mech in front of you to start a bypass mini-game. This will activate it. Follow the mech until it stops, then use the action button to insert a power cell. It will reactivate and destroy a nearby wall. Follow it through the opening and when it de-activates a second time, look for another set of power cells to the right.
Re-activate it and follow it out of the cave into an open area. It will run out of power again. Descend the small ramp and round the corner to the left. Kill the Varren here and pick up the power cells. Return to the mech and power it up once again.
The next time it stops, look to the right for another power cell pickup and use it to reboot your buddy again. It will continue forward and blow up one final wall before detonating itself. Head inside and inspect the ore for 5000 Platinum and completion of the mission.