I got this mp3 Ma797 player for christmas 2009. I can add music to it and the computer detects it through the usb cord. I leave it plugged to the computer for hours, but whenver I take it off it goes dead. Even when I try using a compatible wall charge it does the same. The screen on the mp3 player shows that it is connected to chargers but after hours of being on the charges there is no battery life.