HAOS clean install ECS Z7 Plus won't boot

Hi there – new HAOS user here. I installed HAOS (and later Frigate) on a Beelink Ryzen miniPC last month using method 1 described here: Generic x86-64 - Home Assistant

Everything worked great! No problems.

Acquired an ECS mini-PC configured with an Intel Ultra 7 155h processor, 32G RAM, and 1TB NVMe SSD to give me greater perf headroom and frigate sppt for openvino. Followed the same approach as above, but during the boot sequence I only see ‘Slot A (OK=1 TRY=1)’ on the boot screen. HAOS doesn’t boot. Retrying it results in ‘Slot A (OK=1 Try=2)’ and so-on.

I reviewed all the online topics I could find. Ensured I have UEFI boot enabled, secure boot disabled. Also tried disabling virtualization, ME, and other items in BIOS. Doesn’t resolve the issue. Tried installing Ubuntu on the same machine and everything works fine. My problem is specific to HAOS.

I noticed that my ECS machine refers to the NVMe boot drive as /dev/nvme0n1 and thought perhaps the grub bootloader couldn’t find the correct boot info. So I ran the following commands which had zero affect (didn’t make things any better or worse):

efibootmgr --create --disk /dev/nvme0n1–part 1 --label “HAOS”
–loader ‘\EFI\BOOT\bootx64.efi’

Any additional ideas or recommendations for resolving this? Thanks in advance…

Tried everything I could think-of to fix this and nothing worked. Many proposed solutions on reddit are mini-PC vendor specific and involve BIOS settings that aren’t available on my ECS system. SO… I stumbled across this post for configuring HAOS to boot without EFI support and this worked for me. My system has EFI support but these fixes apparently bypass some of the EFI-specific configuration issues in my BIOS. Posting the link here in case it helps others: https://www.reddit.com/r/homeassistant/comments/1d7fy79/you_dont_need_uefi_to_install_haos_heres_a_simple/