Back in the Navigation Room the SC will tell you that you're now safe from being frozen by the SA-X, but that still doesn't stop it from being a significant threat. The SC will inform you that you can't utilize the Ice Beam ability due to the Metroid DNA (we'll see about that), and that the Federation has prepared an Ice Missile upgrade to be downloaded from Sector 5 (ARC). Leave Sector 6 and ride down the Sector 5 elevator to reach the final unexplored sector. Once there the SC will show you the map and where to find the Data Room, but alas, it's sealed by a Level 3 Security Door.
We'll need to first find the Security Room and unlock Level 3 doors - all in a day's work. Beyond the Recharge Room you'll find a shaft leading down. Down the very bottom are two sealed yellow doors, so we need to find another way through. Jump up to the ladder on the left wall and climb to the top. From here aim over at the right wall and fire missiles to break open a narrow tunnel at the top of the alcove. Crawl through to find a door leading into a gigantic room filled with blue Chute Leeches. Drop down to the bottom of the room and make your way over to the door in the bottom right corner. Through this door you'll enter a huge freezer environment. This frozen area's filled with blue Xs, but of course they can't hurt you anymore.
Watch out for the charging enemies as you descend this room, and note that you can reach the Data Room from here once you've unlocked Level 3 Security Doors. Drop down as far as you can in this room, eventually you'll find a floor section down in the right corner filled with Speed Booster blocks. Run over through the door up on the left then clear out the enemies in the following corridor. Run back into the larger room to activate the Speed Booster so you'll break through the blocks in the floor. From here make your way down to the bottom right corner of the room and go through the door there.
Use bombs to break through the walls in the following room, just watch out for all the enemies in here. The next room contains a large shaft leading down, so drop down to the platform below. The door to your left eventually leads back up into the large frozen room (you can see it lead back on the map), so shoot out the floor here to reveal a shaft leading further down. Drop down and head left. Save your game in the next room before continuing on. Cross the next corridor while jumping over the large green creatures, don't worry as they can't hurt you. Proceed through the next frozen room to finally locate the Security Room, so hop onto the pad to unlock Level 3 doors.
We'll now go back up to the large frozen room to track down the Data Room. Leave this room via the left door and ascend the tall shaft in the next room (bomb the left wall further up to reveal a ladder leading up). Save your game in the next room through the door at the top of the shaft, then go through the following corridor to reach the large frozen room again. Go up through the door just below the red door on the right wall and shoot open the shutter in the following room.
Head through the next door where you'll find the Data Room waiting. Step into the pod to download the awesome Ice Missile upgrade! Now you'll be able to free enemies the same way the Ice Beam could, and the SA-X is included. We now need to head back to the Navigation Room, but thanks to the shutter in the previous room we'll need to find another way around. Go through the door on the right and shoot out the floor in the next room to open up a tall shaft below. Drop down and grab hold of the ladder on the right wall, in here you'll spot several Rippers flying around.
There's a door up below the one you entered the room via, freeze the Ripper with missiles to use them as stepping stones to reach the door. Inside you'll find Energy Tank S5.01. Back in the tall shaft, drop down to the bottom and crawl through a hidden tunnel in the bottom right corner to locate a hidden shaft beyond. In here you'll be able to find Missile S5.01. Once you've grabbed the missile head back out to the adjacent shaft and go through the yellow door. You'll now be back in the tall shaft where a green creature was sitting idly at the bottom. An X will hover down and merge with the creature, turning it into a tall green/purple pillar. Freeze the creature and use it to the reach the floor just above. Once up above go left through the door.
The next room beyond this corridor has a wall with Speed Booster blocks on it so we'll need to dash through to break it down. Destroy the creature crawling along the roof twice and wait for the X to merge with the green creature sitting near the door. The pillar that appears will bridge the small gap between the pillars (you'll see what I mean when it happens), so once the pillar's frozen you'll have enough room to build up some running distance.
Walk over to the far right edge of the platform but not before freezing the pillar. Quickly run over to the left and shoot the door open as you go. The Speed Booster should kick in and you'll break through the wall in the next room. Climb up through this room and go through the yellow door above to reach the giant frozen room once again. Climb back up this room (there's a hidden passage leading around the area where the Speed Booster blocks cover the floor) and go through the door way up in the top left corner. You're now back in the gigantic room filled with the blue Chute Leeches.
Make your way over to the yellow door on the opposite side of the room and head through. As you go through this room though you'll hear loud noises and a giant shadow will streak around in the background. Whatever this thing is, you'll be facing it soon. Inside the next room fry the huge creature on the roof before it can attack, then in this room you'll be able to find Missile S5.02.
With the missile in hand go through the door on the left. But as you enter this first shaft, the screen will begin flashing red and you'll hear a female voice saying "Emergency in Sector 3," the music will also go crazy. What's going on now? Quickly head up to the Navigation Room to gain more intel on the emergency from the SC.