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I have a Dell D600 laptop. It recently refused to start when I pressed its on button. The button blinked for a few seconds, as did the three symbols to its left, which look like padlocks containing a 9, an A and a , respectively.

A couple of times, I removed the battery, waited a few seconds, then put it back in, and tried again. That strategy worked until yesterday. So I had intended to take it to a shop to get an idea of what's wrong.

I decided to try it once more, on straight battery power, and it turned on with no problems.

I usually turn the computer off every night, but I think I will leave it on all the time, now. What's going wrong here, and what can I do about it?

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Does the problem occur when the charger is plugged in ? – Shekhar Mar 11 '11 at 13:41
  • The BIOS is involved in most power-management functions on a PC. Make sure you have the latest version.

  • Your A/C adapter may be going out and needs to be replaced.

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Laptops do occasionally build up a latent charge while charging the battery, which results in the unit not powering on, removing the battery causes the laptop to discharge the built up charge. Sometimes you may also have to drain any residual power by holding down the power button for up to 20 seconds with all power sources, including the battery removed.

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Sounds like an intermittent shutdown fault leaving some bit of hardware in an incorrect state which won't allow it to reset/restart, and that state being maintained by there still being a small amount of power available from the battery. You'll probably find that in this state it was drawing battery power when it should be completely off and drawing nothing, so the battery would have discharged overnight more than you would normally expect.

Removing the battery would remove the power source that is being used to maintain that state, properly resetting the relevant component. It will take a little time for this to take effect as the smoothing capacitors in the power rectifier circuitry will be storing an amount of charge - as very little is being drawn at this point that stored charge will take some seconds (or maybe tens of seconds) to run down.

The problem may be something that can be resolved by a firmware update - check that there are no updates for your machine that you do not yet have.

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