A "pressure" power switch in your lappy...is that a pneumatic or a hydraulic pressure switch?
I myself have a laptop in my car that has a "pressure" switch for ON/OFF. By this i mean that the switch itself has the wiring inside so its impossible to plug any wires there. In my case if you even touch with a single wire the other side of switch the PC starts.... Was really irritating...
I needed to break down the laptop and saw that on the same board there is a different location that relays the link to switch. Then you can try around there with wires wich connection will boot the PC up. I'll add some pictures of my installation for this.