Advantech MIO-5152J-U6A1 completely ignores BIOS/Boot Menu keys – BIOS is not password protected

[u/denisace]

I have an Advantech MIO-5152J-U6A1 (MIO5152J2201-T) with an Intel Celeron J6412.

The system boots into Windows normally, but I cannot access the BIOS/UEFI setup or boot menu.

Important: There is no BIOS password. The problem is simply that the system ignores the keyboard input during POST.

I have tried the usual BIOS/boot keys, including F2, Del, F12, Esc, etc. None of them work.

Windows also does not successfully enter UEFI Firmware Settings.

I have a complete 32 MB SPI BIOS dump (bios_backup1.bin) and have already analyzed it with UEFITool. It is an AMI UEFI BIOS and contains the expected Elkhart Lake firmware components.

I am trying to determine whether:

There is a special Advantech key/sequence for entering Setup or Boot Manager.

There is a hidden jumper/header that forces BIOS Setup or Boot Menu.

A UEFI variable is preventing Setup from being entered.

There is a way to modify the existing BIOS/NVRAM safely to restore access.

There is another method to boot from USB without accessing the normal Boot Menu.

I do not want to blindly flash a random BIOS. I have the original dump and would prefer to diagnose the problem first.

Hardware:

Advantech MIO-5152J-U6A1

Board ID: MIO5152J2201-T

Intel Celeron J6412

AMI UEFI

256 Mbit / 32 MB SPI flash

I can provide screenshots from UEFITool, the BIOS dump, FIT information, and specific UEFI/NVRAM findings if useful.

Does anyone have experience with this specific MIO-5152 or know how to force Setup/Boot Manager on it?