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I've recently revived an Acer Aspire One 531h. I installed Linux set up couple of things for a few days and now, suddenly, when I press the power button, the machine displays the regular press F2 POST prompt but dies right away. After a couple of tries it even dies before the post message appears.

My first thought was bad hdd or overheating. I let the computer sit for a day and came back to it today. I removed the hdd, turned it on and voila - I was prompted for PXE network boot option with no sudden poweroff.

So I turn the pc off and try the supposedly bad HDD in my desktop. The HDD worked just fine, I was even able to boot into linux right away.

Strange, I thought. I put the HDD back in the laptop and it dies right away. I take the HDD out, it dies right away. I even remove the RAM, it dies right away.

So my next guess was overheating. I carefully disassembled the laptop, repasted the cpu, put everything back together - the same thing.

So I am sitting here with a barebones laptop mobo which worked just fine for a week and now won't even get to POST.

I am running out of ideas. I've read that it could be caused by a bad power adapter, but I am beginning to suspect the CMOS battery, because letting the PC sit for a day let it boot again. But as far as I know a pc should boot up even with a bad CMOS battery.

Any advice?

UPDATE: I´ve tried another power adapter and running without CMOS battery but results are the same.

UPDATE 2: I let it sit for the day and I was able to get to BIOS today once again on the first try, but not subsequently. We've checked the cmos battery voltage, which was supposed to be 3V but actually is 2.7V. I am buying a replacement battery today and I will post the esults.

  • It's very unlikely to be overheating, I can tell you that. I did have a similar situation with an old laptop. Sometimes the post screen would appear, and sometimes it wouldn't. Tried a bunch of things, but nothing seemed to have any correlation (though if you did it enough times in a row you could fool yourself in to thinking there was- like your hdd). Never did figure out the problem. Could be something to do with corrupt firmware, or a bad connection on your mobo – Blaine Mar 27 '17 at 11:05
  • Does the laptop have a removable battery? You might try taking out the battery and running only on ac power. Or vice-versa: only on battery, no ac power – Blaine Mar 27 '17 at 11:08
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    If the laptop is old, consider that some electrolytic capacitors may be defective. With a magnifier examine the mainboard, expecially near the CPU. When a capacitor is in bad state sometimes the electrolyte swells the capacitor and the capacitor goes in short-circuit. [images.duckduckgo.com/iu/… – AndrewQ Mar 27 '17 at 11:10
  • @Blaine the battery is long dead and unable to hold any charge at all, all my attempts are ac-only. – rxj Mar 27 '17 at 12:33
  • @AndrewQ The laptop is from 2009 and I did not find any cylindrical capacitors, only these grey squares that I am not sure about being capacitors at all. No swelling however as far as I can tell. – rxj Mar 27 '17 at 12:33
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The problem was caused by torn and deformed contacts on the thin ribbon cable connecting the power board to the mobo

I cut the broken part off, stripped the contacts on the cable and secured it in place with the part I cut off, in order to match the thickness necessary to hold the cable in the latch. Final picture: Fixed

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