Try this, it may get it going:
1) With the unit turned off, plug the small end of the USB cable into the device.
2) Hold the center joystick down (the little squarish button in the center of the scroll pad)
3) While holding the center joystick down with the mini B USB cable plugged into the MP3 player, plug the flat standard USB end into your computer. (Not into a USB hub)
4) The unit should start up and a message come on the screen that says "Transferring..."
5) Give the device 10 seconds ... the hard drive inside the unit should mount on your Mac's desktop
6) You may use the unit as a hard drive mounting it with these steps, or load the unit with music by finding the right place on the hard drive by digging into the folders contained
Tom, April 2010