Anyone have experience getting an HP EliteBook 840 G2 to boot from M.2? There’s only one setting in BIOS to enable it, and it’s enabled by default. Latest BIOS update. It’s in the boot order. It’s even seen when pressing F9 for boot options. I see MX23 but no grub (under legacy) or EFI files found in the ESP partition (under UEFI).

I’ve tried cloning my functional SSD install with dd and clonezilla with no errors, but both result in no boot disk found. Same with a fresh install to the drive from live USB.

I’ve moved through full legacy, to hybrid, full UEFI, but none see the device as bootable after install.

Loading GRUB or Syslinux and attempting to boot from HD also fails to boot from the M.2.

TIA

Edit: added clarification what was being cloned