I have read the many responses here. Most are correct with what to do. I have fixed 100 percent of these systems (DV6000, DV9000) and have not failed again.
You MUST dis-assemble everything and do the reflow for those systems that dont show video but all lights come on.
You will have to do the following;
Clean fan and fan fins, blades and area (must dis-assemble)
after reflow, add arctic silver 5 and copper shims to the GPU, I sell them on eBay under username suthrn1 (but you can do it yourself). You will need 24 ga copper cut at .75 x .75 inch. dont over apply the paste, you only need a small thin transparant layer on the GPU chip.
re-assemble the laptop and turn on.
Once the screen is operational, get online and download the most recent bios and reflash the chip (It would be best to download with another computer prior to turning yours on but the addition of the copper shim will prevent the unit from overheating again (dont forget to remove the little thermal pad on the GPU, if there). The new bios version will set your fan to run at a constant lower speed and wont hurt your system)
For those not comfortable with doing this and are not able to find a salesperson to accomplish this for you at a reasonable fee, I will do the reflow at a very good price. Find me on eBay as suthrn1.
Hope this helps you all out. This is a proven fix. I have a DV9000 running right now after I did the reflow, added the shims and updated the bios. Works like new.