Pick up every interactive item from the garage, then go through the newly unlocked exit. Soon after jumping down to the level below, be ready to IMMEDIATELY run to the tunnel pictured above to avoid the overgrown Xenomorph which will show up on the left. Make sure to crouch, that's the only way to go under the damaged grate.
Move forward. Eliminate regular Xenomorphs in the meantime; don't let any of them stay alive or surprise you. Make your way to the container, which should hide some precious supplies.
Jump into the hole in the container and get ready to evade the overgrown Xenomorph again. Follow your two teammates towards the above pathway.
Resume the offensive against regular Xenomorphs, always looking over your shoulder to make sure to keep them at bay. Further way is very similar to one of the previous scenes - jump into the hole, then immediately run to the partially opened gate, pictured above. Here's where you'll meet up with O'Neal and fight the last battle in this mission.