Latitude D505 Boot Problem

Hello,

 

When I press the power button on my Latitude D505, the green power light comes on for a few seconds and then goes off.  I don't hear any disk activity while it's on nor does the LCD come on at all.  I've tried plugging in an external monitor and there is no video out that way either.

 

The last time it was working, I was running Windows XP and then just closed the lid.  I assume that the laptop went into standby.  When I returned and opened the laptop lid, it would not boot. 

 

I have tried removing all of the user serviceable components (RAM, HD, Optical Drive) with no change in response.  From what I've read on these forums, perhaps the standby switch is broken?  How would I be able to tell if this was the case versus if the motherboard was completely dead?  Thanks.