You must obtain the "Negligence" VHS tape from Dolores' Chapter, see (Dwayne's Memento) achievement guide before you're able to follow this guide. Thank you to (LeXXuz) in the comments for your guidance. You must be outside of a chapter. After you pick the tape up, you must play it in the VHS player next to the TV in the lounge, first floor. After this, if you go into the basement next to the TV in a photo frame there is a vinyl and if you place it into the phonograph, vinyl player next to the TV. The wall where you picked up the vinyl will start to crumble, if you walk in and push the shopping trolley, picking up crates of beer. You will eventually reach the end, continue throughout the course and eventually you'll pick up a glass shard. Which is one piece of the Mirror Mask.