There is no security through the console port (for a connection). If you connect with the proper settings 9600/8N1/noHW and you boot/power up the WX, you should see text in your terminal showing a startup. If you are getting nothing, I would be concerned. The WX4400 has 4 gigabit (only) ports on the front, and an indicator above those that 'breathes' when it is operational. The LAN ports, if connected should light up - only at 1000. If those are working, that would indicate the system is loading proper.
When connecting console, terminal, you should be able to talk to the device. If your settings are proper, perhaps the cable you are using is not proper. Myself, I had a very old 9pin serial cable which worked first time for me so I cannot comment on the specs of the cable; I never looked up that info as was not needed.
You should be able to press enter a few times to at least get a prompt. I have attached a bootup output for your reference.
Bootup from reset/power off. Afterward the status led above port 2, breathes. If not, consult the manuals to determine what error the led may indicate.
I should also note, yesterday I learned Putty does not connect through SSH to this device, seems to be a bug in the sshdaemon in the WX. Connects but disconnects soon as you enter a username. I found another SSH Client that worked passed the login, but refused to "enable" so I gave up as terminal/console access will be adequate for my needs.