At the end I managed to update all BIOS of my machines by using the manifacturer original zip file.
Once extracted there are various files, fun part they changed the name of the main executable that had to be run via EFI with a less obviousy one and also added a FLASH.NSH file where .NSH are the EFI equivalents of .BAT in Windows and .SH in Linux.
So here's the procedure: unzip the ZIP content and put it in a flash drive, at the startup go in BIOS settings and select "Boot EFI shell", when the boot is complete go inside the flash drive content with cd fd0 or similar command where fd0 is your flash drive. At this point I first used the utility provided to do a backup copy of the current BIOS and then ran the FLASH.NSH file, then reboot and remove the external flash drive.
Answer from user3450548 on Stack ExchangeHow to update my AMI BIOS?
Bios update for american megatrends?? --urgent--
How can I update my Bios?
Updating American Megatrends BIOS, unsure what to use.
Any updates to bios should come from the manufacturer of the computer.
More on reddit.comWhy does my PC restart, but the BIOS update never installs?
Can I update my motherboard's BIOS from inside Microsoft Windows (@BIOS, Live Update, etc.) or should I use the UEFI tools only?
The tool says, "Invalid BIOS file." Why won’t it recognise my update?
Videos
Okay. I give up. Event viewer occasionally says Secure Boot CA/keys need to be updated. For other reasons it seemed like the BIOS needed to be updated but it was a hassle so I put it off. But I have no idea which exact utility and variant I need to use to update my BIOS. Sure, we are told to download the correct update file from your computer or motherboard manufacturer's website and etc but it isn't always clear to the ignorant such as myself which is the correct update file and/or utility.
BIOS Version/Date: American Megatrends International, LLC. F3 Y1, 1/19/2022
SMBIOS Version: 3.3
BIOS Mode: UEFI
BaseBoard Manufacturer: Gigabyte Technology Co., Ltd.
BaseBoard Product: B550 UD AC
BaseBoard Version: Default string
This device signature information from the event viewer...
DeviceAttributes: BaseBoardManufacturer:Gigabyte Technology Co., Ltd.;FirmwareManufacturer:American Megatrends International, LLC.;FirmwareVersion:F3 Y1;OEMModelNumber:B550 UD AC;OEMModelBaseBoard:B550 UD AC;OEMModelSystemFamily:B550 MB;OEMManufacturerName:Gigabyte Technology Co., Ltd.;OEMModelSKU:Default string;OSArchitecture:amd64;
Help?
I've found out that my BIOS Version/date is: "American Megatrends Inc. 1.00, 10/19/2017", How can I update it?
I've found this page: "https://www.ami.com/products/firmware-tools-and-utilities/bios-uefi-utilities/" but I'm not sure if this is what I need, or what of the four links I should download.
I'm using Windows 10, if there is the need to know other things, just let me know.
Thank in advance!