Preparations before the final battle | Treatment Plant Walkthrough Resident Evil Zero HD Guide
Last update: 02 February 2017
Search the room where you defeated the boss and you will find two Shaft Keys. Make sure that both heroes have one key. You can now approach the locked door that lead to the next room. Split the heroes and have them stand one near the panel on the right and one on the left. Open the inventory of the first character, use the key and switch to their partner (the first hero can't move when you control the other) and do the same. Note - if a key can't be inserted into the panel, swap places between heroes. Before you leave this place, search the fighting site for Magnum ammo.
The next room (M6,27) is a place where you can prepare to the final battle. Heal the heroes, as they are surely weakened after the last fight. Collect the ammo. Soon, you will start the second fight with the queen. During its most important moment, you will only be able to control Billy. Therefore, he is the one who should carry the best weapons. You should give him Magnum and Grenade Launcher with at least ten grenades. The rest of the slots can be taken by Shotgun, Magnum ammunition and healing spray.
Before you leave this place, use the typewriter one last time to save your progress. Head to the large platform and press the button to activate it. You will watch a cut-scene. When it is over, you will obtain the last document and the battle with Queen Leech will start.