DELL LATITUDE CPI A366XT

i have this computer and it has a serious problem! it will not post or turn on for that matter

i have a battery, ive tryed without and it still acts the same

everything is in (memory batt etc.)

and i still get this problem...

when I press the power button, the screen remains off but the power button comes on then  it will go back off

if the battery is in it will go on, then off, then on then off etc...

can some one help