Chapter 4: The Road to Sanctuary - Borderlands 2
Disembark from the ship then head to the marked location. Examine the Catch-A-Ride terminal. Clear the nearby Fishguts Outpost then grab the Hyperion Network Adapter from a ruined robot on the ground.
Head back to the terminal and install the adapter. Activate the terminal then select a vehicle you want. Ride the vehicle and follow the path. Lay waste on the enemies along the path and continue until you get outside the cavern.
You can explore outside a bit then head to the Sanctuary by following the marker. Once there, kill the marauders outside the gate then use the intercom.
You mission will be updated. Head to the new marker to find an Echo recorder along the road. Continue to the Marrowfield. The entrance is narrow so you have to continue by foot. Head to the marker until you find Riese. Kill the bloodshots pounding him then talk to him to update your misssion.
In addition to the objective to retrieve the power core, you'll have the optional objective to kill 20 Bloodshots. Both objectives are marked in the map so don't hesitate doing it as well while you're at it. Head to the marker to reach Windbreak Camp. Take position and clear the area of enemies. After taking them all out, find the power core and deliver it back to Sanctuary. Examine the intercom to open the city gates. Enter it afterward.
Once inside, head to the nearest marker and talk to Lt. Davis to update your mission. Turn around and remove the power core then install the new one. Talk to Lt. Davis again to turn in your mission and earn your reward.