HP ProBook 6470b Laptop Cannot Boot into Legacy Mode, Only UEFI

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I have an HP 6470b laptop, it was previously working during 5 years with Windows 7 32-bit
in normal BIOS booting mode, with an MBR drive.

I need a tool to overwrite specifically the BIOS part of the firmware.
The firmware update tools don't seem to touch it, only the internal firmware
and UEFI part. If the video BIOS or system BIOS are corrupted, or if Windows
locked or flagged them as malfunctioning for trying to enable VESA for MS-DOS
under Windows, how can I repair the BIOS, the true BIOS that boots into legacy mode
systems, or is this computer permanently with the BIOS broken, and only UEFI now?

I tried to install a VESA driver for Windows XP that supposedly works in Windows 7:
Videoport driver patch for VESA in NTVDM
https://github.com/leecher1337/videoprt

After some hours the computer had the screen totally back without light under Windows,
I pressed the power button to make it hibernate. After hibernating and trying to resume,
it just froze when trying to boot in BIOS/legacy mode. The computer always locks when
I try to boot any legacy mode disk, USB, CD, etc. or any MBR option, it only works with UEFI now.

This is not a problem in the installed operating system.
I have removed all drives, I reflashed the firmware to the latest version,
and removed all batteries so the configuration gets reset to factory defaults many times,
but the computer now can only boot in UEFI mode.

I don't know if a driver that attempts to force enabling VESA modes
for MS-DOS under Windows 7 can overwrite the BIOS and permanently corrupt it,
if it was a virus that destroys the BIOS code, if it is Windows that flagged the BIOS as
malfunctioning for that driver, or some other problem.

Is it possible to recover the MBR boot, or legacy mode, boot options with
some tool (the latest firmware update for 6470b didn't work, I reflashed
at least 3 times from Windows and from the BIOS utility)?

Now I can only boot into Windows Server 2008 R2 (64-bit UEFI)
to continue with an environment that is like Windows 7.

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I have created a BIOS update USB to run it by powering on the computer while holding Windows+B to make a (500) BIOS Recovery, but it doesn't reactivate the capability of booting in legacy mode. The brightness keys work while frozen, but only a black lit screen stays.

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I think that I upgraded the BIOS through DriverMax, and the update disabled

the capability to boot into legacy mode.

Do you know if newer BIOS updates like F.66 or F.74, or other versions, disable

the capability to boot into legacy mode?

It seems that any system update that says "firmware update", "Intel * Series * Chipset * Family Management Engine",

from DriverMax, official, from Windows Update, or from ANY update source,

are dangerous, they could disable thh BIOS and leave only UEFI.

Do you know if it is so? Then those update s were what lef my 6470b laptop

without BIOS, only UEFI, so I can only run Windows Server 2008 R2 64-bit onwards,

no longer Windows 7 32-bit or earlier OSes, and only in UEFI mode.

How can I roll back  my BIOS to the original version? I guess it is not possible

unless I can force nstalling an old version.