Connect it to a PC with USB cable, choice Mass Storage
handsets will automatic turn off.
Step 3 Open Device Manager
Step 4 Double Click the Unknown USB Device
Step 5 Click the Reinstall Driverbutton
C250055
Type
A
Type B
USB Cable
USB port (Type A) on PC
USB port (Type B)
on the player
USB Config :
COM Port
Mass Storage
OK Back
Unknown USB device