Disable the Security System is a mission in Ratchet & Clank, taking place onboard the Deplanetizer. When the Galactic Rangers attacked the Deplanetizer to stop it destroying Umbris, Captain Qwark suspiciously flew off to the Deplanetizer alone, saying he would "reason with" Alonzo Drek. After Ratchet destroyed Victor Von Ion's death ship, he flew into the Deplanetizer alone, though his ship was destroyed along the way, forcing him to sneak on board inside. His first task was to disable the security.
For this mission, you do not have Clank, and as such, cannot use the Thrusterpack. From the beginning, use the Gadgetron vendor to purchase any previously available weapons you do not already possess and spend Raritanium. The Glove of Doom becomes available here for 35,000 bolts. This is a very powerful weapon that can destroy most threats by creating Agents of Doom that attack enemies, though it is expensive, and you may not be able to afford it yet.
Head down the corridor to enter a room with two blarg troopers and a blarg elite commando, which will not see you coming and are easily defeated by shooting from your vantage page. Jump down and head through to the next corridor, fighting some upgraded robomutts, best defeated with weapons such as the Buzz Blades or Proton Drum. A blarg space commando will appear at the end of the corridor; defeat them and hit the button to progress forward to a larger room.
This room contains more blarg troopers and space commandos. It also contains a bolt crank which cannot be used as you lack the Thrusterpack. Instead, head to the path on the left leading to a bridge to the middle of the room. From the left, several blarg troopers will attack, including one from a turret. You can shoot many of them from here, using either the Warmonger or Plasma Striker, and reinforcements will arrive, with more blarg enemies and a more powerful warbot best defeated with the Warmonger or Buzz Blades. This will also open a large door towards leading forward, out of which several robomutts appear. However, after you deal with the robomutts, instead head left first, and behind you will be a ramp for your Magneboots. Head up to retrieve a holocard pack, then head down and go through the large door.
This is a linear corridor that bends a little to the right. Head through, and defeat the blarg space commandos. Make note of the long path on the left of here not marked on your map, necessary for the trophy Et tu, Copernicus? on a later visit, which you cannot obtain yet. Head through the main path, hit the green button to open the door, and enter a large room with bladeballs and a blarg generator; destroy the generator before destroying the bladeballs, and use the Trespasser on the Invinco-Lock to open the door to the next room. This will commence the mission "Head to the Bridge".