Jump down from the crate to enter a huge well-lit area filled with a huge pile of dead bodies.
A cut scene will play of Wesker betraying Excella as she turns into a huge Uroboros. This will happen to the world if Uroboros is released. Not pretty.
In some quick time events, you will dodge the Uroboros until you safely make it inside the ship.
Inside, you will make your way through the ship until you make find a way to defeat Excella. There will be occasional spots where tentacles of the monster will come out of vents to attack you. Press the button in time to dodge. As you make your way through there will be some crates littered in a few rooms that contain ammo, a proximity bomb, and a possible flash grenade. A Green Herb is occasionally in a crate as well. There will be some tentacles blocking your path and you will have to open a door to go around. On the other side climb the stairs and just as you make it to the top you will see some Majini "die" and collapse. Shoot them. Walk over to where it actually dies and you will see more Majini. Use the laser sight to see if they are actually dead. Don't let them get close as a few might be carrying Stun Rods. Kill them all and the last Majini, when it dies will turn into the Clam Guy. The proximity bomb will come in handy and lure it to the bomb and loot the body for the Key Card to enter the Control Deck.
Here, you will find no way to leave. On the bulletin board leading up the stairs, you will find a document stating an experimental satellite laser on the roof. Huh, convenient. Run up the stairs to defeat Excella. At the top there will be two crates that normally contain rifle ammo and an Incendiary Grenade. Open the door to greet your new friend for a surprise.
Shoot the two glowing orbs until they both explode. It will occasionally throw little spawns of itself at you. Killing them will give you herbs to heal and ammo. Take the laser once the two orbs have exploded. Aim the laser at the giant glowing orb until the laser aligns itself on it hold the trigger until the laser stops. Do this about three to four times assuming you hit it every time. The laser will need to recharge after every shot place the laser back to recharge it.
As always, shooting an RPG at it's giant glowing orb will instantly kill it. Saving you time.