@darkxeno Ok you need to ensure that kernel support uefi computers. The could not boot exec format could indicate the kernel doesn’t support uefi.
As for the top post with the iso, that would use memdisk and memdisk only supports bios based computer. I uefi system will throw an error if you try to use memdisk on uefi.
Also try the alternate ipxe syntax I provided.
Lastly on the iso image you have see if there are the uefi directories on that media. /EFI and or /boot