Re: Have you ever had a working PC that wouldn't go into the BIOS mode?

Carlos E.R. wrote:
> On 13/12/2020 02.47, Arlen Holder wrote:
>> Have you ever had a working PC that wouldn't go into the BIOS mode?
>> o <https://i.postimg.cc/GpkgdmxT/cmos01.jpg> Won't go into BIOS
> 
> Yes.
> 
>> How did you resolve that issue?
> 
> Short a certain pin that would reset the UEFI configuration.
> 
> 
> That was one case.
> 
> 
> Another was removing any disk, because the machine was in hibernation,
> and thus refused to accept enter bios till a real reboot happened. And
> the disk said there was an hibernation image.
> 

I had this happen here recently.

It smacks of software having done it (OS into UEFI).
Both PS/2 and USB keyboards disappeared at the same time,
and could not be used at BIOS level. No other setting
was affected. The settings have a crude checksum mechanism,
and there was no message indicating a problem.

It took Clear CMOS to restore function, so I could
press Del (Asus) and get into the UEFI BIOS setup screen.

Clear CMOS is to be done with all power off. No +5VSB
should be present. Many instructions are missing that detail.
Asus on multiple occasions, had to release a one-page PDF
correction to the user manual about this. If you leave
the power running, the Clear CMOS button can short
out the OR-ing diode on VBAT and burn the diode.

UEFI is just a too-insecure technology. As predicted.

    Paul