HP 15-r218na, cannot turn on, 6 seconds of power light, no sound, no fan sounds, no hdd whir

[lkjhgfd]

Please read carefully the whole post in full, this is NOT a hard-drive problem, it is a problem getting power at all, I cannot get to BIOS/UEFI so any discussion of those settings is meaningless in practice for this problem.

----------

My hard drive in an old HP 15 r218na died recently, so I went to change it, this involved a more thorough strip-down of the laptop than I remembered from previous cleaning of the hardware so as to reach the drive.

I have re-seated all the ribbon cables, I have put new thermal paste on the CPU, I have removed and replaced the BIOS backup battery, but I can't get the machine to power on. I was wearing an anti-static wrist strap the whole time, was not wearing anything woolen, and the UK isn't a particularly static prone place at this time of year.

It is definitely getting power, a little light on the AC adapter's input port comes on when I plug the adapter in powered on.

But when I try to power the laptop on with the power button all I get is a blink of another power light on the machine, for about 6 seconds, then nothing. Total silence, no sound of a fan starting. No pre-boot screen appearing.

I checked with a mutlimeter and when the ac adapter is in there is 3.3Volts on some of the ribbon cables to the power button circuit board, so that is getting power. It clearly senses the pressing because when the button is pressed there is a 6 second burst of light on the bottom left corner (near the headphone jack) white indictor LED.

Everything I tried with the Ac adapter in I also tried with the battery in, no success.

I have stripped it down and re-seated the cables several times now.

Please help.

Can anyone find full proper schematics of the laptop, most websites refernecing this laptop model are useless, dedicated solely to fixing things which don't matter until after an OS boots anyway, so I can't find anything worthwhile there. Or any detailed info about boot sequences and light flashing times?

I get about 6 seconds of light on the LED starting from the moment I RELEASE the power button, no beeps, no screen backlight, nothing else, not even the fan starting or the hard-drive's (new one of exactly the same make and model as original fitted) whir.

Thank you

P.S. I have all the kit for fiddly soldering and am good at it, but that's no use unless I know that a ) there is a damaged electrical part, and b ) which one and c ) have an actual schematic and explanation of what happens during pre-boot powerup

P.P.S. The orange light on the keyboard under the wi-fi enable key (F12) also flashed for the 6 seconds that the power LED flashes. But no backlight appears in the screen, and the light under the power button itself never lights up.

[lkjhgfd]

Well what a glorious help THIS forum has been.[/s]

On the other hand, the laptop itself magically started working again after a few more cycles of disassembly and re-assembly. No clue how, but it runs now and seems to be back in good health. Didn't do anything differently between the times it failed to power on when reassembled and the time it just started working again, but it works now.

[Sanjay96]

I have exactly the same problem as yours. Is there anything else that you would advise besides disambling and re-assembling?

[lkjhgfd]

I don't frequent this forum, so it is good luck I noticed your post, I'll provide all the advice I can remember:

Start when you dissassembled the laptop and tried to reassemble? Or did it start from a closed-up working laptop? I'm afraid I have no clue what made the difference to get my laptop working again, but it is working reliably now and I'm typing on it this very second. All I can suggest is waiting several hours with it disassembled for any cleaning solvents used to fully evaoprate away. Possibly gently lifting out the RAM modules (wear an ESD wriststrap) and reinserting them well. Ensuring all wire connectors are well fitted, especially the screen wire which is a hideous monstrosity of very fine loose wiring inside if you're unlucky enough to dislodge the protective wrap around it, if you can avoid ever trying to disconnect this screen wire then just leave it connected throughout disassembly procedures. Ensure the HDD and other slot connected things are pushed in well. Try taking out the BIOS battery (little coin cell on the motherboard) for tens of minutes, I did this and it reset my BIOS/UEFI to sort sort of basic configuration, it didn't seem to help anything for me, and since doing it I don't have the BIOS/UEFI options I had beforehand, but it was something I did between the times of trying to boot up unsuccessfully and the time I booted and got to the BIOS/UEI screen. Also, don't try powering on the laptop at any point except when all wires are reconnected and the casing is all back together. You can physically leave the keyboard not clipped in (but ensure ribbon cable is connected properly) and leave the screws out when doing sch test reassemblies, but it seemed for me that I succeeded when trying to boot a reassembled device but not when trying to boot up the motherboardwith all cables connected but no casing fitted (casing may act to put pressure on some vital contact somewhere or something). That's all I can say really, I still don't understand what these horrid failures were, or how they suddenly recovered such that I was able to boot and reinstall linux on to my newly fitted HDD. You might use some very sharp voltmeter probes to make the checks on the little board which is under the power switch, see if they are the same as those I reported, but I still don't know what to interpret from them, only that if yours are very different to mine your problem might be very diferent in terms of cause. And maybe post your problem with as much detail as you can on multiple computer forums, particularly those which discuss internal hardware a lot and are filled with people who discuss the circuit level details. Repeat every "test" or "measurement" you can deduce I did in my first post, and include your results for them in any forum pots you make. And, if you do find an explanation as well as a solution, do please post it on this thread (and PM on this forum me so I get an auto-email about it), I'd love to understand what dark magic went on behind the scsnes in my situation too.