- Do you have the ESW connected to a network that has a DHCP server such as UC520? If so you may want to check on the DHCP server what IP address is assigned to ESW 520 (MAC address binding). If its a UC520 - then CCA can discover this for you - note make sure you connect the uplink port on the ESW to the UC520 expansion port

- If the ESW is standalone connected back to back to your PC - have you gone through steps 1 through 8 in Section 2 at the guide below:

http://www.cisco.com/en/US/docs/switches/lan/csbms/esw500/quick_start/guide/ESW_500_Quick_Start_Guide.pdf

- If you are using a console cable - make sure the right settings are configured - check page 49 at link below:

http://www.cisco.com/en/US/docs/switches/lan/csbms/esw500/administration/guide/ESW_500_Administration_Guide.pdf

If you have tried all of the above - can you factory reset the ESW and try one of the above?