Another Dell but it too didn't power up when the button was pushed. It turned out Dell had a new BIOS out. Be sure to check at Dell.com for updates on BIOS, motherboard drivers at the very least.
Also, test without ANY USB devices plugged in.
I have a Dell Inspiron 13 5000. A few months ago I started having problems powering on my laptop, I'd sometimes have to press the power button multiple times for it to turn on. My laptop would also lose 5% power overnight while it was shutdown. I've had my laptop for a little over a year and one day it would no longer turn on, the blue light would go on indicating that the laptop was charging and I could hear that something was on but it wouldn't boot up. I took it to a repair shop and was told I have a bad motherboard. They tested the voltage: my laptop could take in power but the motherboard was not functioning. My laptop ended up turning on a after I picked it up from the diagnosis but the repair place said it was still a bad motherboard (could go at any moment, likely won't last a month). Is this possible? I've been doing what I can to figure this out but aren't getting anywhere. It's a new system and I heard that newer motherboards don't use beep codes anymore. I ran Dell's diagnostics and a diagnostic from Intel but both came up clean.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic