That looks pretty normal so seems is it's a grub thing(or something else) but same as you I can't find anything about it, the other thing you could try is to install another bootloader. Either Refind or Systemd-boot, but I think those require your system to be efi boot. Do you know if your system is bios boot or efi boot?
It may also be worth a try change the following setting to 0.
Then update grub: grub-mkconfig -o /boot/grub/grub.cfg and then reboot without monitor and see what happens.Code:
EFI variables are not supported on this system.
i suppose it doesnt support efi and that timeout it didnt worked but thanks for you effort