Thanks UWE!! You got the problem right.
But How to diagnose which component failed.For this I will have to open the access panel in order to see the internal LEDs on the system board and that too while the server is powered on.
Also, This problem happened after I inserted the HBA in the PCI slot by taking out the Riser cage and then put it back.May be the cage didnt set properly.After that I took out the HBA from the PCI slot, closed the panel and tried booting the server.But, it did not come up and that internal health LED was as before.
please guide me to solve the problem..