ACR5F000-M12-971015-R01-C3EN as we saw in one of your videos.
From the Everest report, we saw that the video bios in your laptop has the version;
1.2R2.5 as you previously stated.
The BIOS file you have downloaded, extensa 355 supposed bios.7z , appears to be a
correct bios update file for your Acer Extensa 355.
(and this webpage supports that theory; http://www.gklaus.de/infos/acer/biosstring.html )
The 355r01d0.bin file has this Bios Identification string within it;
ACR5F000-M12-980317-R01-D0 and that bin file has this text within it for the video bios version;
1.2R3.0a so I agree with you that that is good.
I'm not sure whether or not if 'Aflash.exe' can be run from other than a floppy.
I am somewhat horrified that you apparently ran the flash program from Windows, even to try
and make a backup of the current bios.
As this laptop does not have a floppy or CDROM, I wonder if you have another HD that
you can clone the Extensa HD onto, so you have a certain bootable backup copy of it.
Also, or additionally, make an ISO of the Extensa HD.
booting to DOS from your Hard Drive (that's pure DOS, not C:\Windows), (without
any memory managers,), exactly as if your HD only had the Windows 98
Boot Disk files on it.
Best if this DOS were booted from C:\ directory and place the bios update files AFlash.exe , msg.dat
and 355r01d0.bin in this same C:\ directory that this DOS is in.
(If you can't boot DOS from C:\, at least make sure those 3 bios update files are placed there.)
(I believe you already have a copy of the current bios stored away in another HD?)
Anyway, see if AFlash appears to work to make a copy of the current bios to the HD.
If that seems successful, try updating the bios using the filename 355r01d0.bin (that
filename contains number zeroes, not letter 'O's.)
If the flash is successful, afterwards when you reboot, you may need to go into the bios screens
and 'load defaults' - maybe not.
Think about it, you seem knowledgeable enough to reason out what you're doing.
Now I have to go to work.
EDIT: seems like AFlash (Acer Flash) only works from the floppy drive. Nevermind, I have
another suggestion that I'll ask the OP about, if he is able to do.