I have an old acer extensa 4620Z which I just disassembled, removed the CMOS battery and reassembled and it's still asking for a password.

One thing I read is that you should leave it for 10 to 15 minutes, I left it for a 3 - 4 minutes, can this actually make a difference, if it has no battery, then should it matter if it's 10 seconds or an hour? Does this have any merit?

Other than that, I'm stuck, what can I do about the BIOS password?

  • Of course it makes a difference. There are various capacitors present in or near this circuit. – Daniel B Mar 22 '15 at 20:54

I've read anywhere from 30 secs to 25 minutes (even one site said a few days) to wait after removing the CMOS battery. I've also read that some laptops have a "hidden IC which stores the password" or that the password may be stored on a sector of the hard drive. You might remove the hard drive and see what happens.

This site http://www.biosflash.com/e/bios-cmos-reset.htm has pretty good coverage of what can be done to reset the BIOS.

You also may be able to calculate the backdoor password for your particular model though I didn't see anything from a quick search.

And you can always try contacting the manufacturer via there support site but you may need some way of proving ownership.

  • The method, does not seem to work for notebooks. – Trufa Mar 23 '15 at 0:11

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