I take it that the usb stick in front has the image to reflash on it??
have you got any others or a HDD connected ?? disconnect everything .
unplug and restart without any sticks or HDD connected..
Can you communicate with the box through FTP or telnet??
here are some possibilities from the HOW TO section:
Telnet! with (Backup) Spare import process (Guide)
Solving Problem "Starting" in Vu Plus
