Unfortunately, this part is no longer available.
Sadly, this type of problem is very common with Coby products, which are extremely low quality and have very short service lives. It doesn't take much to damage them, and they frequently fail all on their own. It is actually a wonder that yours has lasted this long.
Coby products were such poor quality that they actually went bankrupt about 4 years ago - there is no support for their products in any form, and parts are difficult to come by. In the case of the battery, it is not stocked anywhere at this point, but even when it was available the cost of the battery was about $45, which just isn't worth the investment for this type of portable player, when you could buy a brand new player from a more reputable brand and get a warranty, for about the same price: http://amzn.to/1Xtlodk
Best regards, ***** ***** for the news,
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
Although you’ve already paid your fee to the site, I am only compensated for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a 5 star rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately. Rating 1 or 2, or not rating at all, does not produce a refund, it only penalizes me for trying to help.