I don't like ITUNES and I recomend generic MP3 players but the sad truth is.
Lithium ION or poly batteries are the problem
Is you over discharge them they grow cystal short and explode
If you over charge them the grow crystals short and explode
If you over vibrate them they grow crystals short and explode
After three years the chemistry becomes unstable and charging or discharging becomes unsafe which is why most LION batteries shut down three years after manufacturer date.
Thats right you battery in your cell phone or camera will do the same thing