Hi Kannan,
I have seen a 5000 and a 7000 recently with this issue. The recieve power over PoE, and will boot up, but they do nothing else.
I plugged them in and ran a packet capture while directly attached to the ethernet interface, and I saw no traffic. There is no LLDP or CDP or DHCP or anything.
I also tested the protection isolators and they appeared to be ok, so I suspect the ethernet transceiver ic has failed.