MY COBY MP4 PLAYER WILL NOT TURN ON, CHARGE, REGISTER ON ANY COMPUTER, AND I GUESS A LOT OF PEOPLE HAVE THIS PROBLEM, so it's just black like it's cardboard or something, please help!

My coby mp4 player wont turn on at all, I have tried resetting it and the screen is still black. I connected it to the computer and tried to charge it all night, but it still wont come on. Wat do I do??? I left my coby mp4 at a friends, and he accidentally turned it on and ever since it burnt out, It won't do ANYTHING! it's so frustrating, but yeah I have the same problem. does anybody know what to freaking do? It just stays black like it's a piece of cardboard or something, it wont charge. thanks.