The next upgrade is sort of optional and the hint system never actually tells you about it. It is extremely useful though and you should definitely get it before going after the Varia Suit. By this time the hint system will be pointing to the next upgrade which is the Morph Ball Bomb and you may want to go after it now, in which case skip ahead to the next page. Getting the Morph Ball Bomb involves fighting a boss and you may want the Charge Beam's extra fire power for the battle. On the other hand you save a bit of backtracking by getting the Morph Ball Bomb first.
Go back to the Main Plaza, get to the upper section and follow the ledges over the Nursery Access door to the bridge. Before crossing it's a good idea to take out the two wasp's nest on the far wall so you don't get swarmed. Follow the ledge right to a door after crossing the bridge.
Ruined Fountain Access
This is a tunnel with Scarabs similar the ones you seen earlier, but there are roots partially blocking the way, hence the need for the Morph Ball. There are actually three groups of Scarabs here, but one of them you only see if you're going the other way.
The floor of this room is filled with toxic water. It's not a good idea shoot the Plazmites wandering around since the room will be very dark without them. Work your way to the right around the edges of the room, pausing by the fountain to scan the Chozo Lore. The first door quickly leads to a dead end for now, so hop the stepping stone to the next door three quarters of the way around the room.
This passage is guarded by Shriekbats, a common enemy in this section of the ruins. The best way to get the scan is to hang back when you reach the corner, then look at the ceiling at the end of the passage. Shriekbats are dangerous for their size so keep an eye on your radar to tell you where they might be lurking. Try to shoot them before they notice you, or while they're in the air preparing to attack. You can also backtrack out of their path so they collide harmlessly into the wall.
When they're gone, continue to the next door, use a missile to clear it, and go through.
This is a large room with toxic water on the floor and a tree in the middle. The are ledges leading up but you can't get very far this way, so you need to get across the room to the next door.
The game plays a bit of a dirty trick on you in that the ledge you need to get to isn't reachable from the water, so if you have any thoughts about just wading across you can forget them. Instead, look to the left to find two ledges guarded by Reaper Vines. You can't destroy these but you can make them retract for a bit by shooting them in the eye. Cross to some ledges on the tree and hop up to a bridge. Turn left and follow the ledge down, dealing with more Reaper Vines at the bottom, to get to the door. Clear the shield and go through.
Gathering Hall Access
There are some leaky steam pipes here which fog up your visor, but nothing more dangerous.
This is a large room with several levels and Blastcaps in several places so watch your step. There are ledges to reach an exit at the top level but we'll cover that in the next page. Stay on the ground level and follow the hall on the right. But before going through the door there, take a quick scan of the ceiling to find some Shriekbats; these won't attack unless you're coming from the other direction, so you might want to clear them now so you're not taken by surprise later.
Save Station 2
It's a good idea to save your progress here, then go back. If you're starting here from a save, or if you didn't clear the Shriekbats mentioned before, they will attack now. Go straight across the Gathering Hall to the remaining door at ground level.
Watery Hall Access
There are Shriekbats here so hang back at the corner to get them in their roosts. Follow the ramp down to some toxic water, but look to the left to see a cracked wall. Fire a missile to break through and collect a Missile Expansion. Cross the water and follow the ramp up, then deal with more bats and fire a missile to clear the next door.
This is a large U-shaped room with toxic water covering most of the floor. There are ledges which allow you to get around on the upper level.
There is a puzzle to unlock a metal gate up ahead. You need to locate and scan four runic symbols scattered around the room. You might as well start scanning them now instead waiting until you reach the gate and then backtracking.
Start by clearing the Blastcaps from the stepping stone on the left, then hop over to it. Turn around and check to the right of the door where you came in for the first symbol. There is a Reaper Vine guarding the next stepping stone, so shoot it in the eye and continue along until you reach another stepping stone with Blastcaps. The next symbol is underneath the Blastcaps so clear them and scan the ground underneath. Continue along the stepping stones to reach a ledge at the other end of the room; the third symbol is behind it. Go back to the door you entered from and scale the ledges on the right. These lead to the gate you want to open, but proceed carefully since there are Reaper Vines guarding some of the ledges and you don't want to be taken by surprise. When you reach the last ledge, check to the right to find the last symbol. Finally, scan the fifth symbol on the gate and it will open.
Collect the Charge Beam and Eyons appear on the walls. You can use the Charge Beam to destroy them now though. Scan the inscription on the back wall before you go. Go back to Save Station 2 to save your progress. The Charge Beam, while useful in battle, doesn't open any new areas for you so there are no further expansions to get now.