I would personally use the serial cable that came with the ZD and access the CLI.
Note: config Putty with 9600 in the speed setting for the serial option
To start with you can issue the following:
ruckus# show config
Protocol Mode= IPv4-Only
Device IP Address:
IP Address= 192.168.40.100
Gateway Address= 192.168.40.1
Primary DNS= 192.168.40.1
VLAN ID= 1
You could then use the IP address to gain access and change the IP back.
If you don't have a console cable you could use Wireshark to sniff the ARP from the controller.
In the filter box in Wireshark issue the following:
eth.src == insert mac address of controller here
It should then show the ARP entry and present you with the IP address of the controller
If you need a manual for the CLI:https://app.box.com/s/e7injt517cmq2uetqthpp33ymvhx8865
Also do you have a DHCP Server, if so check the DHCP server against the MAC address of the controller and obtain the IP that way.