Yes, it is possible to change the battery. You will need to find one the right voltage and size. Most MP players are 3.7 volt. You also have to take your player apart and find out how much space you have and how difficult the battery will be to remove.
I have changed the battery in an Icelander type player and the battery in a chipod. However, my other chipod the battery connections are soldered really close to the board. I wouldn't attempt that one.
The one I bought for the Icelander was a iPod nano battery. It's a tight fit but it works.
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 ops: 1GB Black Hacked Chipod ops:
2 GB Black Temptation Player 
8) WHITE MEIZU M6 8GB 8) |