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