Can't boot error: invalid magic number

Hi,

I'm going to boot my serial console with Memtest86 v7.4. I put the BOOTX64.efi in sda4.

gurb.cfg:

menuentry{
      set-root=hd(0,3)
      linux /BOOTX64.efi
}

When I boot the machine, it shows
error: invalid magic number

press any key to continue...

I think we can boot .efi file right?

With Grub2 looking for sda4, you need set root=(hd0,4). It counts drives from zero, partitions from one.