HELP! dead m6!

I brought a M6 off the internet yesterday. No problems,amazing player, until i charged it. It came with full battery and it ran out quicker than i expected,but i just put this down to the small charge the factory puts on it in production. So i charged it. However, as i charged it, the battery actuality went DOWN. I've tried another usb cable to no avail and someone suggested running the battery down and i tried that and now it wont turn on! And if it does it comes up with the charging screen and it says after a second" fully charged" when the battery icon at the top right of the screen says no battery at all and it shortly turns off! Advice please?

If you are using a shared USB hub the player may not be drawing enough charge. If you are using a dedicated USB port and you have tried another cable then the player may have a faulty battery.

Thanks! it turns out i mistakenly pluged it into a USB 1 socket not a usb 2 !! my bad! thanks for the help though