After you acquire the Grapple Beam in Artaria, you proceed through Dairon to reach Ferenia.
Reach the E.M.M.I. Zone
Go through the door on the right. You can optionally use the Total Recharge Station through the tunnel at the bottom right. Use the Grapple Beam to pull yourself up to the Grapple Swing Point, then swing to the tunnel on the right and go through. Use the Grapple Beam on the blue walls above you, and go through the tunnel between the two blue walls. Use Flash Shift to go past the pressure plate and go left to the next room.
Use the Grapple Beam on the Grapple Swing Point in the ceiling to reach the upper left ledge. Go through the E.M.M.I. Zone Door on the left.
Through the E.M.M.I. Zone
Kill the small flying robot on the left, then use Flash Shift to get past the pressure plate and reach the next room. Slide into the tunnel on the left and you will fall through some Pitfall Blocks. There will be an important cutscene.
Robot Chozo Soldier
When the cutscene ends, a battle begins. Jump and use Flash Shift go to the robot's other side whenever its arm turns red. You can do the same when its arm turns blue, or just jump to a different ledge to dodge that attack. The robot can also shoot three beams at you, or a single, powerful beam. Dodge all these attacks as you shoot it with missiles or charged shots. Repeat these strategies and it will eventually be defeated.
Get a Missile+ Tank
If you wish, you can review the dialogue from the cutscene by pausing the game and pressing L to see the Mission Log, then scroll to the cutscene in question and press A.
You can Speed Boost as you shoot the door on the right and go through, then Shinespark next to the door that you just came out of, to reach the blue wall on the upper left, or just use your Grapple Beam to get there. Then roll through the tunnel above the blue wall.
Speed Boost while running toward the fan, then when you are at maximum speed, repeatedly wall jump upward against each platform, and at the top, tilt downward on the left control stick to ready a Shinespark, then go to the tunnel on the left and press ZL to slide into it, then press B and tilt down-right on the control stick to perform a Shinespark downward through the Speed Booster Blocks to the left of the Missile+ Tank. It is difficult to do, so don't worry if you don't make it. Just speed boost past the fan and jump upward to get past it.
Go through the bottom left door of the room with the fan. You will reach an elevator room. If you didn't get the Missile+ Tank, you can try to Speed Boost from here, then ready a Shinespark in the room with the Missile+ Tank, wall jump to the top and slide to the left side of the tunnel, then press B and tilt down-right on the control stick to perform a Shinespark downward through the Speed Booster Blocks to the left of the Missile+ Tank.
When you are ready, go through the door to the left of the Missile+ Tank, then use the elevator and you will go back to Dairon.
Get a Missile Tank
Shoot the door on the right and go through. Step on the glowing panel to get a briefing and save the game. Then go through the lower left door.
Shoot a charged shot at the box in the way. Go down below and go through the E.M.M.I. Zone Door. Jump over the gap to the left and go through the E.M.M.I. Zone Door on the left. Keep going left, and enter the tunnel at the bottom left. Roll left to fall through the Pitfall Blocks there. Go through the door on the left, then jump onto the platform above the robot and go to the left, and go through the door to the left of the robot.
Go left, and down to the bottom of the room. Enter the Morph Ball Launcher at the bottom left and drop a bomb to activate it. Afterward, go left through the room where Corpius is still in the background, and go through the door on the left.
Go left and drop down below, then go right and drop down below. Shoot the bottom right floor to open a secret passage. Use the Grapple Beam to destroy the Grapple Beam Block on the left, then roll through the tunnel and take the Missile Tank.
Go to Burenia
From the Missile Tank, shoot through the floor to go down below. Go to the right through the E.M.M.I. Zone Door. Go to the right and down, then go to the left and down, then go to the right and down, and go through the door on the left. Slide through the tunnel on the left, then slide through the next tunnel, then use the Grapple Beam to grab the upper left wall. Go through the E.M.M.I. door on the left.
Make your way through this straightforward room, then go through the door at the end to reach the shuttle to Burenia.