YP-S2 no longer turns on???

Greetings! Got a little problem with my YP-S2.
The little bugger seemingly wont turn on and play any music. I cant get any light to flash whether plugged into the PC or not, and have 'reset' numerous times still with no result.

I can however, access the storage drive and still transfer music back and forwards whilst connected to the PC. But still no flashing of little blue/red/green lights...

I'm guessing the battery might be shot??? Any idea where i can buy new ones (is it fairly stnadard or something obscure) and how on earth do i change the battery without smashing the thing to get into it?

Thanks,
Aron