So i was working on that PCG-V505EXP Sony vaio. I finally got the harddrive out and switched it out for one that works.

When i put the computer back together... It would not power on. Most of the time I can see the light turn on for 1-2 seconds and then it dies out. Sometimes i dont even get power! What the heck is going on. I need to get this computer to work. I made a promise...

I don't thinik it is the power Adapter since the power on light on the adapter still comes on. And the laptop turns on for 1 second. any ideas?

Any ideas would help.

Did you connect the Hard disk drive correctly?
Jumper it correctly if necessary?
It's a difficult problem to solve with just "I took it apart and when I put it back together it didn't turn on." type of thing.
You could check that the power supply area inside the notebook isn't damaged/disconnected in any way maybe.

I'm at a loss for what to tell you based on so little, and I didn't ever open up a Sony Vaio laptop much before, so I'm not really sure what to tell you.

Check HD install, check power supply output with meter, and then tell us what you find.

yes, read: http://www.techspot.com/vb/topic53864.html