Dropped Dv7 will not post

A good friend of mine asked me for some help regarding her older dv7 laptop (Q9000, 4gb, 4650)The notebook was dropped on the floor and the screen cracked. I connected an external display and proceeded to boot up the system. All the lights on keyboard come on, fan can be heard and the HP logo is displayed on external screen. Unfortunately the system shuts itself off after 20s. There are no led error codes and system does not post.

I've tried removing hard drive, battery, hard reset, resetting ram/replacing ram. All this results in same result: shuts off after 20s and no bios post. Once (and only once) was I able to get into the diagnostics screen to run some tests (after resetting the ram) but again system shut off within 20 seconds. Also tried booting holding down win key and B key (which from what I understand loads a previous bios). When I tried this I get blinking leds (3x) which should indicate a problem with ram, but there is no image output to screen or post/boot. I also believe the hard drive is shot from the fall (not recognized in bios on another laptop)

Is there anything else I can try? I was really hoping I could at least get the system working with an external screen. The fact that video was being output to an external screen gave me a glimmer of hope. If there was a problem with the motherboard itself, would I even get any video output? Internal screen also works (although shattered)

Thanks

 

Did you check the heatsinks and fans?

 

Not as of yet. The idea of it overheating crossed my mind but figured it was some other issue since the fan was spinning and was getting error codes pointing to the ram.

 

Assuming there are two sticks of ram, have you tried using just one (swapping them if the first try fails) and changing the socket the single sticks are inserted in?

 

Of course. That's one of the first steps I tried.

 

Didn't mean to offend. From you description I wasn't sure exactly what you had tried and I've found that even the best troubleshooters sometimes skip over what later turns out to be obvious.

Good luck.

 

Did you try another hard drive in it?
Was it running when she dropped it?

 

I have not tried another hd. I wanted to make sure I could reliable boot into the bios before going that route. Not sure if it was running.

I completely disassembled the laptop and inspected the heatsink. Seems fine, nothing obviously wrong though 1 screw seemed loose. Replaced thermal compound and reassembled laptop. Notebook now asks if I want to run diagnostics when I boot up (correctly recognizes that there is no hd in place) but still shuts off after about 20s.

I did however notice the fan does NOT turn on at all when the machine is switched on. Granted, its only on for a short period, but wouldn't the fan normally at least be spinning when the is first switched on and is sitting at the diagnostics screen? I was sure it ran yesterday, but it could have just been my other laptop nearby. I will likely disassemble the notebook (again) and test the fan with an external power supply to see if it runs. Any idea what the fan specs are? According to service manual I need part number 516876-001.

I'm thinking that the issue could be fan/heat related. Maybe the notebook is shutting down to prevent thermal damage if the cpu/gpu aren't being cooled.

 

Made it into bios albeit very briefly 30s (i guess it will post to bios) Diagnostics tests show ram is ok and only error is no hard drive (I removed it) There is also an option to have the fan always running (which is set to on) but fan def does NOT spin.

 

Fan/heatsink looks fine. Replaced thermal compound and reassembled. Unfortunately, still same problem -> shuts off after certain amount of time. First boot up lasted about 90s, 2nd time about 40s & displayed some graphical corruption on external screen, 3rd boot up about 30s. Still seems as though its heat related. I'm guessing the gpu cooling is to blame because of the graphical corruption on 2nd boot. There is only 1 heatpipe that runs from the copper plate covering gpu to heatsink, so its possible that it is no longer functional (though I didn't see anything wrong with it) Sigh...

At this point I'm wondering if its worth spending more time messing around with it. Seems that a new cooling assembly goes for about 40$ on ebay. I did consider rigging up a frankenstein cooling system from desktop cpu heatsinks just to test it out. Hmmmm...