Tyrant room: (Rebecca and Billy)

Move straight ahead; you will see a (cutscene (a non-interactive cinematic the game plays automatically)) and then face the Tyrant.

Ignore the door nearby for now.

Let Billy use his handgun ammo on the Tyrant while you attack with the shotgun.

Retreat if the Tyrant gets too close.

Alternatively, if you are confident, you can run past the Tyrant (avoiding damage) with Billy in front and you behind, allowing you to knife it when possible.

If the Tyrant focuses on you, run away as Rebecca has limited stamina.

Avoid making mistakes, or use the shotgun if necessary.

After defeating the Tyrant permanently, move to the end of the area.

Flip the switch.

Head up the ladder.