The exit button allows to remove a card from the 
  reader and returns back to the election screen. It does not 
  shutdown
  system. To shutdown the system you have 
  to change registry HKEY_LOCAL_MACHINE\Software\Global Election 
  Systems\AccuVote-TS\Shutdown to 1 and change it to 0 to exit to 
  windows.
   
  Dmitry