[Elecraft] KIO2 Stopped Working

[Daniel E. Salo]

My KIO2 was working perfectly until I tried a new computer interface 
cable in the microphone jack (the SSB module is installed).  It's 
possible that there was a short in the computer interface connector, 
but that has been fixed.  

Now, after removing the computer interface, the KIO2 appears to be 
dead.  

The PORT menu option is set to ON. 

Using K2Remote and Hyperterminal, I'm not getting any response.  The 
serial cabling is the same as before.

Where do I begin troubleshooting this situation?