There are two ways to proceed now. If you want to help the marines get rid of the first group of Weyland-Yutani mercenaries, I recommend going a little to the right, taking the place as shown. From here you'll be able to easily eliminate any approaching enemies. Watch out for the stronger one; use explosives against him, they work best. When he dies, he should drop a full set of armor.
If you don't wish to waste time aiding your allies (they'll can deal without you) or if you've already gotten rid of the first group of enemy units, go left, towards the stairs leading to upper galleries of the hangar bay.
Turn left and interact with the terminal pictured above, which is responsible for arming the first emergency release. Stay on your guard because doing so will spawn new enemies in the hangar bay. Ignore the ones downstairs, by the dropship where you're teammates are taking a stand. Instead, attack the mercenaries on the galleries using crates for cover.
Keep moving straight ahead, but stop every time you see a new wave of enemies. After you reach the currently closed control room, turn right twice, killing enemies which show up where shown on the above screenshot. Try to get close to the other control panel you see in the distance. You'll notice a missing fragment of the gallery and receive an update on the objectives.