Answer To "Last Room Escape Puzzle"

You forget about trying to open the doors, that’s just a red herring.

Instead you take the silver cross down from the wall and use it to smash the mirror which, you should know, is not a mirror but a pane of transparent glass between two identical rooms
with identical contents.

Stepping through into the identical room you see that there are two doors in this room aswell but the one to your right is not locked and, opening it, you step out into sunlight and freedom.