Hope somebody can use this info. My problem was the laptop would not boot. When you would press the power button, the keyboard lights up, the fan would kick on, the power light, then the orange charging light would come on. Ten seconds or so later, it would just die. It happened everytime I tried to turn it on.
Bought a replacement motherboard, but after installing it, it still did the same exact thing. The last thing I checked was when I disconnected the LCD cable from the board I was able to boot up multiple times. So I take apart the LCD and checked the inverter then the cable and found the cable was not fully seated on the LCD connection. After reseating it and taping it securely to prevent future dislodgings, I turned it one and voila! It booted up.
Spent a long time trying to fix this (2 months) and it turned up to be something simple like a loose LCD cable. I'm starting to loose my techiness.
So, before you buy any parts for this bastard laptop from HP/Compaq, check your LCD cable.