Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Worked for a while, then malfunctioned

When I first bought this, it worked fine. Found most studs behind drywall, esp if you run it over a few times and verified that you got the same results. However, after using about a half dozen times, it started to act up. Lights would blink constantly (indicating that you need calibration), results were spotty and inconsistent, and oftentimes, it wouldn't even light up at all. I changed to new batteries and no luck. Final straw was when it indicated a stud at a certain part of the wall. I put a nail in and hung up a framed piece of art. Came crashing down and shattered the glass. Do NOT buy this if you want something that lasts more than 6 months.