I figured this out myself but thought I should post the resolution to possibly assist others. I removed the cables connecting the DAE trays to the Storage Processors. I was then able to connect via serial cable to the console port. I'm not sure whey the connection wouldn't work with the storage attached but it wouldn't. Once connected, I launched the browser, connected to 192.168.1.1/setup, reset the IP addresses and deleted the domain information. This is all explained in the Initialization Guide (P/N 300-001-272). I was then able to reconnect the storage and begin configuring the system through Navisphere from a browser connected through the LAN port.
Like some others here, I'm having difficulty connecting to a CX500 system via serial port. I purchased this system used so I have no idea what any of the IP addresses or passwords are. I've read the documentation for initializing the system and I'm certain that my laptop and serial cable are fine. I have a second CX500 which we purchased new several years ago, and I'm able to establish a PPP connection fine on that system using the same laptop, cable and dongle. The used system seems to come up just fine, at least I don't see any amber lights. I've restarted the system several times with no success.   Is there some way to hard reset this system to factory defaults without wiping the OS? Is it possible for the console ports to have been shut off? 
CX500 serial connection