Tson Unprepared, the crew of the Explorer-Class Subcore get mowed down, until they mount a sizeable security force to take them on. However, even then they were unlucky, as multiple system failures and damaged sections work in the Ever Legion's favor, immobilizing heavier assets of the security team and the ones that remained were heavily armored, so the corrosive weapons proved to be VERY effective.
They did put up a fight, though, and 12 Ever Legion soldiers remain. They move towards the bridge and attempt to clear it out, which was understandably under heavier guard, and the "acting captain" was shielded, so it took a while to destroy it. After the 10 surviving boarders cleared the control room, they realize that the ship itself was not controlled by this room, but knowing about drones, they proceeded to systematically destroy the Drone Cores powering systems of the ship with ease.
They do seem to have trouble getting to a certain section, though. It is under a rift-based barrier of an unknown substance, and shooting it doesn't seem to do much to penetrate it. The Subcore is crippled, but despite that it is still sending out a distress call, and a flotilla of Assault-Class Bombers are en-route. The Ever Legion have a short amount of time to think of something.