tested on x1 carbon gen 5 with bios n1mur48w

update thinkpad x1 bios

turn thinkpad on and press f1 to enter setup.

select security > secure boot, set secure boot to disabled.

select security > i/o ports, set bluetooth and fingerprint reader to disabled. these devices are not supported by openbsd. disable other devices you don't use.

select startup, set uefi/legacy boot to uefi only.

press f10 to save changes and reboot.