We have been discussing about the HP DV Series laptop boot up problem in detail and came up with couple of options to solve it but did not had a 100% clue what exactly causing the problem. I was in nothing to loose situation helped me solve the problem some what.
I have mentioned that I have tried normal hardware problem solving methods but nothing worked or solve the issue or able to bot up the computer. However, HP DV2000 laptop start after couple of months later.
Best part is I did not have any clue what makes it start after some times. And it keep on giving the problem time to time.
This time I tries something out of box. Connect the laptop to the AC Power and switch it on. As usual it started all the lights on but nothing else seems to work. Nothing on the screen just black screen, Long beep and two short beeps. Left it for some times and computer was heated up like red hot iron. Then switch the computer off and switch it on. BINGO. Machine started normally. Windows 7 boot up and gone to the logging screen.
Then had change to update the BIOS to the latest version (F39). Problem is not 100% solved I guess but at least now you and me know how to boot it up. That might be helpful for you to backup your files and updated the BIOS as HP website directed.