I had the same problem, called support, new one is on the way.—I think there is a bunch of them that are bad—a lot of people have reported this on this site, call support, very helpful people,
Sansa clips don’t work in sub-zero temperatures, and when they don’t respond, they are not turned off, so it’s a combination of dead battery and temperature.
Fix: Just leave it in a warm place a bit (sometimes a few days) plugged in and turn it on.
In cold weather you should keep the player under your coat, next to your body. Your body heat should be enough to keep the player from getting too cold. When the battery gets too cold, it won’t put out enough power to power the player. If the battery gets much too cold it might freeze, causing it permanent damage. Very high temperatures can also damage the battery.