MB Board Powers-up only for a fraction of sec

[Bagavandass]

Mb: Intel DP55WG with i5 First Gen

When the power button is pressed the CPU fan starts and stops within a fraction of a second. This happens for the first time only. After that, no activity even i press the power button. The LED in the MB is on all the time.
# Replaced the PSU
# I cleared CMOS using Jumper
# Replaced CMOS Battery

No use.

 

[popatim]

Sounds like you may have a short somewhere.
Which LED is lit all the time?