DSL won't boot from USB on T440

[fraggle]

As the title says. I used 

Code:

doas dd bs=4M if=dsl-2024.alpha.iso of=/dev/sdc status=progress oflag=sync

to create the USB since I wanted to play with it on bare metal. dd completes successfully and all files are on the USB drive as they should be.

Regardless of BIOS options on my T440 it just will not boot and loops back to the boot device list.
I've tried CSM on and off, UEFI only, Legacy only, Both with UEFI preference.

Am I missing something with the dd command or do I need to unpack the ISO and change some things?
Maybe I'm missing some obscure BIOS setting that I'm unaware of yet.

Any help would be appreciated.