laptop wont boot

so earlier today i was showing my brother something in windows media center and everything was cool. moments after closing it i had a persistant pop up notification in my system trey saying that it could no longer identify a usb device. the only device thats been connected for weeks is my western digital my book drive and it was working fine so i restarted windows to see if maybe that would get rid of the problem. instead of restarting windows shut down and when it started to power up but before bios or anything else loads it powers off. it does this rather it's plugged in or not so that isnt the issue. i tested another hard drive from an identical laptop and the same thing happens, if i put mine in there laptop everything comes to life so i know thats not it. does anyone have any ideas before i take this thing off as to what may be causing it? my laptop is the hp pavilion DV6625us system stats are in my profile, running windows 7 64 bit rtm build 7600

The laptop won't even POST anymore? in other words it doesn't even load the BIOS screen before it shuts off?

Can you get into the BIOS configuration screen?

no it wont even get that far. it's had no problems before this, i've never seen it.

So it's probably unrelated to the hard drive then right?

before it gets to post it shuts down and repeats itself, it's also not a battery or plug issue, thats the first thing i checked.

yeah i tested the hdd in another identical laptop belonging to my sister and it works fine in hers, also if i put her drive in my laptop it has no effect on the problem

are the fans spinning?

fans work fine just tested it.

I know you said you checked the battery but what did you do? Did you try booting it with the battery removed (plugged into wall only)?