The Hp dv9000 series is known for all of a sudden not booting or showing a boot screen.
First steps I take are more visual than anything. When you power on the laptop does your screen only stay black or does it look sort of gray ( like a light is on but no text on the screen ) ?
If this is the case, then you probably have nothing more than a defective lcd panel.
The next step I would take if the above is not true would be to plug in an extrenal monitor while the laptop is powered off. Once you have the extrenal monitor plugged in, power on the laptop. If the external monitor does not turn on, try pressing FN-F4 once and once again see if the external monitor powers up. If not, press FN-F4 one more time.
If you now get a picture on the external monitor but not the lcd panel of the laptop, you most likely have a bad lcd cable.
If you still do not get anything on either monitor, I would suggest removing and reseating the memory in the laptop along with removing any other inserted cards.
If you still have no picture on your lcd panel or an external monitor, your most likely culprit is the motherboard itself. In this case, I would suggest a phone call to HP. Even if the laptop is out of warranty, it can't hurt to call them. That specific model may be under some extension to the warranty or may also have some other circumstance that you are unaware of that requires them to fix and or replace the machine.
Hope this helps,
Edited by techextreme, 14 December 2009 - 03:09 PM.