AcerPower SP - Bad Power Button? How To Test?

Hope someone can make sense of this...

When I push in the power button, the power light goes on for 2 seconds or so. cpu fan spins, then everything dies - no boot-up, screen display - zip. I can keep pushing the power button, and the same thing happens over and over.

Switched out the power supply, cleaned motherboard and all connections, switched memory in bays (memory new - about 4 month old). Battery good.

The reason I was thinking that the problem was the power switch is because I know it was acting buggy for awhile - sometimes you had to press it two or three times to get the computer to come on.

Whats the easiest way to test the switch (today) without ordering a new one? Can I bypass switch somehow and have computer on all the time? Any other troubleshooting suggestions?