MacBook Pro 2007 - yesterday was working fine, closed the lid and unplugged from charger. About an hour later tried to use it, it was powered off...when attempting to power on, it starts for about 1-2 seconds then shuts off. (When I say it "starts" that just means I can hear fans spinning and the hard drive, screen is black and within 2 seconds of hitting the power button it "clicks" off). If you hold down the power button for a few seconds it will stay powered on but the LED on the front flashes, when you release power button it shuts off. I have tried removing the battery and it does the same thing. The battery had a full charge and powering up with just the battery connected does the same thing. Today I purchased a brand new Magsafe 85w charger - no change in behavior. I have tried everything that Apple says to do, all the resets, removing battery/charger and holding down power button. I have removed and swapped out the RAM. The odd thing is that when I remove the RAM and hit power, the laptop will stay powered on and the fans will spin, but of course nothing boots and it makes a sound like a car horn continuously. It does not shut off unless I manually power it down. There has never been any water damage or other physical damage to this machine and it hasn't shown any other signs of trouble in the past. I disassembled the laptop and looked for any obvious signs...nothing. I was able to pull the hard drive to get my data so I know the hard drive is working. So the question is...do I need a new logic board or is it just the power board? If its not the motherboard, I can do the work, I'm a computer tech but don't deal with MacBooks normally. I can take it to the Apple store but its not close to my home so I want to try everything possible on my own first - and there's no warranty or Apple Care.