Another mission you need to complete in Ransom Keep is to Destroy all the 4 Silos in the area. This guide will show you the location of all 4 Silos and how you can destroy them to complete the mission.
As you infiltrate the territory, you are greeted by a gate blocking your way. Grapple to the side to get into the Ransom Keep. When you get inside, go to your right and raise the 1st Fuel Silo there. You can use a heavy weapon to destroy the Silo after it is raised.
Go out and turn right on the first fork and turn left. There are 2 Silos here and I recommend raising them simultaneously to make the mission easier. Use a rocket weapon like the M41 SPNKR to destroy the Silo.
You can also use the Blast Coils outside the area and throw them into the Silo to destroy them. Keep going north until you reach the fork leading to the right. The last Silo is in here.
Be careful, more enemies will be chasing after you destroy the 3rd Silo. After raising the Silo, destroy it using a Coil to complete the mission.