Are you able to view other status information in the Control Center?
cat and tail CLI (Command Line Interface) commands can be used to view log files after you access the appliance as admin using ssh clients.
For example, Control Center log file (BrightmailLog.log) can be viewed as follows:
cat /data/logs/bcc/BrightmailLog.log | more
For details, please see the topic titled "Administering Symantec Messaging Gateway through the command line" in Symantec Messaging Gateway Administration Guide.
Hope this helps.
For the issue where you can't access logs from the Control Center, I would recommend generating a diagnostics from the CLI and opening up a support case for assistance
Regards,
Adnan