If your VoiceLive 2 exhibits these symptoms here are some things you can try. 

Check to see if the unit passes audio and the footswitches work.  If the unit passes audio and the footswitches seem to be working, then you most likely have a defective display. 

Sometimes if you cycle the power very quickly on the unit it will not boot up into normal operation causing the screen to appear blank.  
Try recycling the power slowly to see if it will boot into normal operation.

If you were attempting to update the software on the unit and it was power cycled manually during the update, you may need to recover your unit with a MIDI update.  

The unit will usually display a blank screen with the Home button lit, will not pass audio or be recognized as a USB device.  
Attempt to update the software via MIDI as stated in the manual.

If further support is required, please contact us via a support ticket from the Music Tribe Community Portal