Sony DSC-P73 Cyber-shot wont switch on?

I have a problem with my camera, it wont switch on.
If I press the power switch the green LED comes on for about a second & then nothing.
If I then break & reset the power circuit ( opening & closing the battery compartment ) & press power again the same thing happens.
I don't think it's humidity as I've tried drying it out.
I haven't worked on a digital camera before, so I don't want to go into it without a circuit diagram.
Can someone please help.