Laptop problem

[#1]

I have been asked to look at a laptop for a friend, who diagnosis was 'its not working right'.....  When I got it, I suspected a bloated windows install, and worst case it needing a reinstall.
When I tried to power it on, the fans kicked in, and the screen went from black to a grey color indicating the backlight was on, but nothing else. 
HDD light was flickering away happily.  I shut it down, and tried again, this time it got to the screen where you can pick some option to get to the BIOS etc, and then the screen went black again.
Left it for 10mins, and came back. This time I got it to the login screen, but it started to give some graphics corruption, and then shut the screen down again.  Again HDD light flickering as if working OK. Fans are on all the time at this point.  Managed to get it to the BIOS screen and it seemed stable for a few mins, but fans still howling.
I shut it down, and I have left it for a week in my cupboard.  Got it out again tonight, and it immediately booted up fine, and I got to the desktop, but then the fans have kicked in again, and graphics corruption started, and then the screen went black.
Switched it off, and on again, got to the BIOS, and it stays there OK, but fans spinning loudly.  unfortunately no CPU temp in the BIOS.
i have pulled the HDD, and tested it, just in case, but my feeling is an overheating issue, as tonight after a couple of mins, it was throwing out red hot air.  Before I go pulling it to bits, to clean the heatsinks etc, (need to do this as there is no panel on the underside to access CPU), this graphics corruption worries me.  Could there be irreparable damage to the chips, making cleaning it out a waste of time????  Its an HP Pavilion DV6000

[#2]

Clear out the heatsink first then walk away if there are still issues.
The HP (and Dell) suffered from badly soldered graphics chipsets which failed over time.
Try with an external monitor to see if that helps but if it is hammering out hot air then there is something wrong there somewhere.

[#3]

Thanks
I have been reading up on people reflowing the GPU on this laptop.  Seems a waste of time doing this..  I have only ever reflowed a PS3, which is still working 
I will pull it to bits tomorrow, and clean it out, and put new compound on the CPU.  Does the GPU need compound as well here, as it appears to be held down with a separate heaksink, attached to the CPU one?

[#4]

Depends if it is using a thermal pad or grease - generally though a small smear will be beneficial anyway after cleaning off any old gunk.

[#5]

Any chance the GPU is on a plugin daughter board?
The Toshiba I'm using right now went all glitchy a long time ago. All distorted and coloured lines but was OK in VGA  and Bios mode. Repair shops and the like said it's scrap and can't be repaired. Took it apart and I could see the GPU was a plugin board on the motherboard.
Bought one off ebay with a smashed screen, swapped the part and it was perfect. Even had the bonus of an additional memory stick from the scrapper.
Best thing was I resold the scrapper on ebay, to someone who wanted a different part, and got my money back as well.

[#6]

From the images I have seen online, it looks like its a chip soldered to the motherboard unfortunately.

[#7]

I note DomS's comment that HP Laptops can be affected. I have a Pavilion dv6 just over 2 years old which suddenly refused to run up. They have a series of codes flashed on the Caps Lock key to indicate where the problem may be. In my case a single flash repeated continually said the CPU was in trouble. I have the maintenance handbook which reveals that the first item to be plugged in when building the machine is the CPU and all the other parts follow in layers, all of which did not appeal to me. A replacement CPU  (AMD Phenom III N950)  would be an expensive shot in the dark so I invested in a new Lenovo E535 which was the last W7 machine my dealer had left and was at rock-bottom price. So far it runs well. The HP HD is OK so I transferred all my personal stuff without any problem therefore avoiding much of the not very helpful HP stuff that came with the old machine.  I have not actually booted the HP out but may try to do something with it if I am bored one day!!

[#8]

Graphics chip soldering issues are common on certain HP laptops.
Shame it's not the older NC 6000 as I can get them apart with my eye's shut.
I have reflowed a couple of graphics chips on my own HP NC 6000's, you need a very fine point soldering iron & a magnifying glass to see what your doing.

[#9]

Well it does look like its the graphics chip.  Stripped it down this morning, cleaned alot of crud and fluff out of it. Rebuilt it, but still the same.  managed to get into the recovery options, and graphics corruption not as bad, but still glitching, and even though the fans not running as much, its pumping out pretty hot air. 
I suspect its overheated recently, and damaged the GPU.  Unfortunately its probably uneconomical to repair.
I will see if it blinks any error codes to me, as colin mentioned.

[#10]

How old is the laptop? Can it be returned to the supplier under warranty?

[#11]

HP laptop warranty is normally:
12 months for consumer machines.
36 months for business machines.
The warranty length is normally on the white info sticker stuck on the bottom of a HP laptop.

[#12]

If there is an inherent fault you have recourse for up to 6 years but you will have to prove the fault is inherent.

[#13]

Its a few years old and I would be very surprised if its under any kind of warranty to be honest