I have experienced the same issue with my Vivosmart 4. I loved it but could feel the sensors as they flashed for some reason. I then slowly noticed during charging sessions that a red mark was beginning to appear where the sensor lights usually sat. The lights clearly left my wrist with with a burn. The skin was red, textured differently, and has begun to peel since i stopped waring the device. This experience is very concerning and dangerous to users.
