[The Torminator]

Originally Posted by Aksker

They can fit I think But event the volts are the same, mAh are different. And I do not know about them from my mp3.

Yes, voltage is same for any single cell battery. mAh generally just means how long the battery last. No good to know what yours is. I would go for dimension then.
Can't say either the battery really is your problem. Can you connect the player to your pc?