hp pavilion zt 3000 cannot power up

I have this hp pavilion zt 3000 laptop that cannot power up after successfully shutting down yester nite.
When you press the power up button the light for battery and power on go on and the one for the haddisk momentarily goes on then off but you do not see any display on the screen nor do you hear the harrdisk spin nor the fan spin . Please help what could be the problem.

I have so far removed the cmos battery ,memmory, hardisk and then returned both but the system still cannot power up , please do help.