I have an HP Paviion dv9008nr Entertainment -black screen at boot

step one, big battery out? skipped that?
step 2, a good power pack , that means 19vdc on those 2 pins.
bingo BIOS screen now work ,yes?
step 3, try an external VGA screen at the P15 VGA jack there
screens work now (BIOS first) yes/no?

remove DVD, drive
and all USB devices
there booting with only 1 memory stick. (got more?, try each 1 by 1)
black screens of *****'.

the lack of flash codes, Implies Power pack is dead. or CPU overheated, and selfshuts down. that fan going dead tells
me the power park is dead.

http://pcdied.com/#black-screens

This is a bad problem.
If you wrong changed booting, booting is impossible.
You must boot from a rescue disc, and configure after the bios.


JMG

Try this links:
Troubleshooting No LED Lights Glow During Startup or Boot HP Notebook PCs - Troubleshooting Blink Codes or Beep Codes that may Occur During Startup or Boot , or BIOS Beep Codes - For Hp and Compaq Desktop Computers (United States - English) Troubleshooting Black Screen with no Error Messages that may Occur During Startup or Boot HP Notebook PCs - Troubleshooting Black Screen Error Messages that May Display During Startup or Boot HP Notebook PCs - Troubleshooting Blue Screen Error Messages that May Display During Startup or Boot HP Notebook PCs - Troubleshooting Windows Logo Screen Error Messages that May Display During Startup or Boot Using HP Support Tools to Update HP Software, Drivers, and BIOS with Windows 7 . Using HP Update Tools to Update HP Software, Drivers, and BIOS with Vista Updating the BIOS or ROM for Notebooks Running Windows XP Updating Drivers and Software with Windows Update

The mother board may have a problem. Go to www.hp.com and select support. Enter your model of the laptop (or product number) and check to see if they'll fix it for free. There have been recalls on the issue in the past.

1. Power on (NO Disc.)
2. Press Pause
3. Enter 314159(with remote)
Display will show "FF"
4. Quickly press "0" (for all region)
5. Press pause
6. Power off and powere on after 20 secs.

get it repaired under the limited warranty scheme
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01087277&lc=en&cc=us

hi,
if nothing(even hp logo ) is not coming on the display then please try this.
1.remove the battery and then press the power button for 30 sec.Again refix it and check.
2.If windows sound is there then this mught be the issue with display.

3.If there is no windows sound might be the issue with RAM so please get it checked.

Your tx2-1020us is not compatible with the KN745AA as this device is only compatible with the following:

• HP Pavilion dv2700 Entertainment Notebook PC series

• HP Pavilion dv6700 Entertainment Notebook PC series

• HP Pavilion dv9700 Entertainment Notebook PC series

• HP Pavilion dv2600 Entertainment Notebook PC series

• HP Pavilion dv4-1000 Entertainment Notebook PC series

• HP Pavilion dv5-1000 Entertainment Notebook PC series

• HP Pavilion dv5-1100 Entertainment Notebook PC series

• HP Pavilion dv6-1000 Entertainment Notebook PC series

• HP Pavilion dv6-1100 Entertainment Notebook PC series

• HP Pavilion dv6600 Entertainment Notebook PC series

• HP Pavilion dv6800 Entertainment Notebook PC series

• HP Pavilion dv6900 Entertainment Notebook PC series

• HP Pavilion dv7-1000 Entertainment Notebook PC series

• HP Pavilion dv7-1200 Entertainment Notebook PC series
• HP Pavilion dv7-2000 Entertainment Notebook PC series

You can find the compatibility chart by clicking here

You can find the compatibility information for the ES631AA by clicking here

To resolve your issue you should purchase one of the following:

To dock your notebook you need the HP QuickDock KN744AA#ABA or

You could get HP Notebook Media Docking Station

plz try by resitting the ram if you dont know how to open the laptop then i will suggest you to take it to repair shop.

Remove you battery and disconnect power supply. Press power on a couple of times. reconnect power supply but leave out battery. Press power on. Hopefully machine will boot now.