Few steps to analyze if the Barix device is dead.
- If the device is not announcing the Sonic IP, try by using the Discovery Tool (available on the Barix WEB site) 
- If you still cannot reach the device, then force Factory Default. Depending on the firmware on the Barix device you have a Tab "Defaults" on the WEB Interface or depending on the HW you can do that by long press (>10sec) of the Reset button.
- If none of the previous action is successful you may need to do a Serial Resue. see http://wiki.barix.com/index.php5?title=FW_Update
- finally please contact your Barix distributor or Barix Support for help or a RMA