@siheobs OK so now we know what boot mode this system is using, bios. So you should be adjusting the BIOS exit type.
So SANBOOT, EXIT, GRUB, and GRUB first HD all failed to boot the system.
This is thinking out of the box here…
Search forscanfor internal
and change it toscanfor internal,hdbios,external,biosexternal
The for BIOS exit mode, change it to rEFInd. This most likely will fail but it would be interesting to see if this chameleon can boot.
Disclaimer: The issue here is how iPXE’s boot kernel can find the first hard drive in these systems. Its a bit out of the FOG Project’s control how this component works.
Also since we are dealing with Lenovo systems here, ensure your firmware is up to date. We have seen some flaky firmware come on newly released models.