How can I turn the MacBook on without the top panel?

I wondered if this were possible?

As far as I can see the button unlike other laptops/computers doesn't fire a physical connection you can override but sends a signal through the combined keyboard cable.

Is there anyway other way of powering it on as it struck me that maybe my macbooks problem is stuck keys which is why no extermal keyboard worked - the boot was being jammed by multiple keys being considered down.

I figured if there is a way of turning it on I should try it as one last test before selling for parts.

Thanks.