I'm working with an older laptop; a Compaq Presario V5101US. I've had it sitting around for awhile, plugged up but unused; I actually had it hooked up to my TV with the goal of using it to play streaming video, but never really used it for that.
I'm guessing it has been plugged up and unused for about 4 months.
Today, I decided to use it, but now I can't get it to come on. You can hear the fan underneath power up, and the hard drive appears to be spinning (I can't swear it, but I took off the cover and touched it slightly, which make it grind a little), but it never "beeps" during boot, and the screen stays black.
The Caps Lock button stays off, and so does Scroll Lock. Holding in the power button does nothing (I held it for 30 seconds to hard reset, but nothing happened), and connecting it to an external monitor does nothing (the monitor stays off, as if nothing is plugged in).
I believe that the USB is working; I had a wireless keyboard attached to it that seemed to charge.
I took out the battery for about 5 minutes, hoping to reset it, but that had no noticeable impact, either.
Based on the above, I've ruled out the hard drive, screen, and CPU (else the fans and USB wouldn't work). Bad RAM doesn't seem likely, either, so... bad mother board? That's the only thing left, other than software, right?