I opened a laptop pavilion dv3 case to clean the fan (which I wasn't able to anyway!).
After putting it back together the laptop won't turn on although the battery is fully charged. I notice that when I removed the board that has the power button on, there is a flat black connector that got disconeted from the laptop. Could that be the problem, if yes, how do i put it back in.
Thanks so much, this laptop is not mine and I'm panicking now that I ruined it for good.
In my opinion your best bet is to take a look at the service manual and make sure you plugged everything back in. It should show all the cables and where they belong somewhere in the manual.
But first just try this since it sounds like you just forgot to reconnect the power button (I've done that countless times and it's always a relief finding out that's my problem and not something serious). If that's the case go to page 71 of that manual and it will show you where it connects and give you a general idea of how it connects. If that's not the problem let me know and i'll see if i can help anymore.