System is a laptop, namely a HP Pavilion dv7-4060us Entertainment Notebook PC. Upon pressing the power button, CPU fan spins up, then spins down to nominal speeds, caps lock light blinks once per second, WLAN light is a solid yellow/amber, and the LCD screen does not power on at all (as opposed to powering up but being blank) so there is no indication of POST.
This points right away to some sort of hardware failure, since the computer is by this point an eight pound paperweight.
Removed battery, HDD, RAM, CMOS battery for 15 minutes.
Reinstalled CMOS battery, RAM, battery. Connected AC adapter, same symptoms occur.
Checking HP’s support site for the DV7 gave no indication of HP even acknowledging the issue even exists.
A quick Google search gives various articles but the first two are the most relevant. This is from the first forum post:
“I’m on my sister’s laptop right now because when I went downstairs earlier my own computer decided to ‘check-out.’ Came back, black screen, flashing caps lock, tried to reboot, tried the hard reboot, nothing.
“Found a forum where some whack job with the same problem wrapped theirs in a sweater for 30 minutes and it fixed the problem. Click to the next page, tons of people swearing it works. Apparently, the intentional overheating causes it to power down appropriately then reboots. We’ll see if that works.”
While the second post appears to shed a little more light on the problem:
So I take it home, try usb bios reflash, no go. Capslock light blinks, no other lights, sounds, nothing.
Ok. So I open it, get my harborfreight heating gun and heat up both the video chips. The AMD one and the ATi one. As shown in picture below.
As soon as I put it all together and plug it in, it starts working and has been, constantly since two weeks ago. This laptop has not been turned off, standby nothing. Works perfectly. Sound, video, HDMI port all alive. Still switches video cards when you unplug the power adapter.
Hope this helps.
Also, this same solution worked for a Compaq Presario CQ60. That laptop didnt pickup the bios reflash either no matter what I tried. Turned on immediately after heating the video chip.
This reminded me of the Xbox 36’s Red Ring of Death (There’s even a wikipedia article for all the issues it had!) and the first solution people found for it: The towel method. iFixit later came up with a more elaborate method that, like the post on Notebook Review, targets the culprit component: the video chipset.
The DV7 was turned on, wrapped in a blanket, and left alone for half an hour. When the time was up, the laptop was turned off and let cool down for fifteen minutes. Powering it gave the symptoms. Laptop was turned on again, wrapped in a blanket, and then in another blanket, and left alone for two hours. When time was up again, laptop had powered off by itself. Unwrapped it, let it cool down for fifteen minutes. Power on gave POST, along with a helpful error message from the BIOS complaining about there being no hard drive installed in the system.
Hard drive was reinstalled. Powering on gave POST, then Windows boot. Windows didn’t seem to have any problems apart from having the wrong datetime, but that was expected since the CMOS battery was taken out. Device Manager reported no hardware issues
Since the hardware is now suspect, I told the owner of the laptop to better start saving for a replacement. At least now the whole thing turned from an unexpected monetary outlay into an expected expense. What gives me pause is that the DV7, like the Xbox 360, also has an AMD Radeon video chipset, so it could indicate an issue with AMD’s fabrication processes and that other laptops that have come out with the same chipset or components from the same AMD manufacturing lines will have the issue as well.