Portable massage guns are a popular way to ease tension. Although it's a rare occurrence, experts say massage guns can be a fire hazard if their lithium-ion batteries overheat. There are several posts on social media where people said their massage guns burst into flames while being charged. Inside Edition enlisted the help of Fire Marshall Brian Schock and the Wallingford Connecticut Fire Department to show what could potentially happen if your massage gun is overcharged. He says you should always read your massage gun's instructions and always charge your device according to the manufacturer's guidelines.