An absolute bs. They invested so much in the visual effects that they forgot to allocate resources into the plotline.
Spoilers ahead ( Although it really doesn't have a story)
Kid opens a book and plays a casette, kid's mother gets possessed by some weird spirit. Kid's mother kills and massacres all the families along the building. Everyone turns into zombies and tries to kill a little girl and a woman and it backfires. Fun fact , the survivors were just attacked physically whereas in the end we see the spirit possessing another resident of the apartment.
An absolute waste of time. Although if you prefer movies without any story , go for it.