Resident Evil Zero Walkthrough #5
The Treatment Plant

Walkthrough #5 - The Treatment Plant

Leaving the elevator, make your way to the Control Room and interact with the Power Supply Panel

To restore power to the Treatment Plant You need to light all points by pressing 3 of them;
With each button pressed all points 2 points away will also get lit.

These are the points you need to press:

After restoring the power use the elevator to get down

Keep moving forward until you reach this area where you will need to fight a Mimicry Marcus then go through the door at the end

Pick up the Treatment Plant Map

Make your way to the Reservoir's Room to save Billy

After saving Billy return to the room shown below

In this room, you will need to make a way to the other side to pick up the Handle;
Have Billy climb down the ladder, get over the wooden crate and push the steel crate to the wall as shown below

Go to your initial position near the ladder and switch to Rebecca;
Have Rebecca use the device to rotate the machine right

Switch to Billy and push the wooden crate straight to the end

Push the steel crate to the wall

Switch to Rebecca and rotate the machine to the left (or right, either work here)

Switch to Billy and Push the wooden crate as shown below

Switch to Rebecca and rotate the device to the right

Switch to Billy and push the wooden crate to the end then climb up the ladder

Switch to Rebecca and use the device to Fill/Drain

Walk over the floating wooden crates and pick up the Handle

Go open the door using the Handle

Climb up the ladder

Put the Red Chemical in Rebecca's Mixing Set and climb back down

Proceed to the Lodgings and save the game

Keep moving forward until you reach the elevator and use it to get down

Move down the path and prepare to fight The Tyrant… again

The last tactic won't work this time because of the small space so, use a powerful weapon like the Magnum to decrease his HP or even eliminate him;
(If you're playing on Hard Difficulty and want to save magnum ammo, use a couple magnum shots on him and switch to another weapon; even if he deals damage to you, you can just heal up in exchange of magnum ammo)

After defeating The Tyrant, push the button and climb the ladder

Pick up the Motherboard and climb back down

Get back to the elevator, go up and put the Motherboard in the machine to restore power to the Gondola

Have Rebecca ride the Gondola

Turn the lever to close the floodgate

Exit the room and pick up the Industrial Water

Add the Blue Chemical to the Red Chemical in the Mixing Set to make Sulfuric Acid

Combine the Industrial Water with the Sulfuric Acid to make Battery Fluid.

(you know that from the Files "First Investigation Unit Notes" and "About Battery Fluid")

Get down the stairs and switch to Billy

Get down using the elevator and make your way to Rebecca

Give Rebecca a boost to get the Empty Battery

Combine the Battery Fluid with the Empty Battery to get the Hi-Power Battery

Get upstairs and go through the door and you will arrive to where you saved Billy

Keep going forward and put the Hi-Power Battery in the Forklift

Have either characters climb the wooden crate while the other press the lift button to reach and grab the Keycard

Now it's better to go save the game so, do so and return here

Go all the way back to where you picked up the Empty Battery and proceed to open the door by using the Keycard

Keep moving forward and get ready to fight Queen Leech

This monster has a lot of HP and is the most annoying to deal with, so use all of your magnum ammo on it.

After defeating Queen Leech, have each character pick up a Key

Use the Shaft Key (R) on the right and the Shaft Key (L) on the left

Heal up, pick up medicine and ammo and save the game then activate the lift;
Get ready to fight Queen Leech Stage 2

Go all out on Queen Leech;
Have Rebecca's settings on Idle and Solo and get her out of the way (Check the video below);
Use your strongest weapons against Queen Leech (You will only need Handgun Ammo for later even in hard mode)

After the cutscene, you will have to distract Queen Leech to let Rebecca open the windows (Rebecca moves on her own);
Have Billy shoot Queen Leech to grab its attention away from Rebecca;

You only need to grab the monster's attention; you win after Rebecca successfully opens the windows.
If you need to heal up Rebecca, open the inventory and switch to her from there and heal her up.

Here is a video showing how to defeat Queen Leech on Hard Difficulty:
Youtube Video

Congratulations, you completed the game

After completing the game, Leech Hunter Mode and Wesker Mode are unlocked;

In Leech Hunter Mode, you try to pick up leeches and you get rewards depending on how many you've picked up, the top prize being having unlimited ammo on any weapon you own.

In Wesker Mode, you play the game normally while having Billy as Wesker with special abilities.

You can also try and complete the Steam Achievements to 100% the game.

The End

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