Louis,
Set an valid IP address to e0M port (Must be in a different network from data network - Ex: Different VLAN). Its recommended to configure using System Manager
Connect through OnCommand System Manager using the new IP address.
If you want to use the same IP, cable the e0M port, then turn off the e0a port and configure the e0M port.
filer> ifconfig e0a down
filer> ifconfig e0M 10.x.x.x netmaks x.x.x.x
Remember to update /etc/rc and /etc/host files. If you have another Ethernet port, its recommended to configure using System Manager.
PS: e0M port is 10/100.