???????
Have you finished it already? This might come out as a spoiler
Anyway, he was burned in the fire and then was sent to a hospital. He could have survived though. He called out to yoonbum everyday and when a grandmother who stayed in the room beside him (or near) heard his cries everyday and all the time, she finally had enough and she decides to suffocate him with a pillow to shut him up.
(づ ̄ ³ ̄)づ