Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Melted itself open

I bought this heater last year and used it all winter very happily. It worked very well and kept my computer room comfy and warm.This year i brought it out to use, plugged it in and on the second day it started turning off on me after about 3 min of use. I unplugged it and let it cool off since it got amazingly hot after that 3 min and i discovered the black, round casing with the holes in it that goes around the top, had melted itself open in the back.I loved this heater last year but can only give it 2 stars due to longevity.