A:AnswerI don't think you can replace the battery on these, I think you just have to buy a new MP3 player. Given how the one I have works, it's kind of worth going ahead and getting a new one.
A:AnswerThey do not open but sometimes get frozen in a setting. I believe you just hold down the on/off button for about a minute and it will reset. If that is not the correct way to rest it, email Sandisk and they will reply with the proper reset method.
A:AnswerIt can get pretty loud, with files at standard volume being unsafe to listen to on headphones at max volume. It mainly depends on your speakers/earbuds, I'm guessing.