I downloaded 'Armbian_25.11.2_Odroidc2_trixie_current_6.12.58_minimal.img.xz', flashed it to sdcard, and it booted fine.
As a sidenote unrelated to the issue at hand, my first try was with the sdcard on a device with emmc, and in this case the boot process stopped after block-local (?), and dropped to initramfs shell prompt.
I have not tried to build the image myself. I wanted to flag that the file linked for download was not correctly assembled. I should have been more precise.
As of 2025-12-01, current 'Armbian 25.11.1 Trixie Minimal / IOT' lists as 'Kernel: 6.12.58, Size: 505 KB, Release date: Nov 22, 2025' and seems to have had problems on image generation.
Please check when possible.
Thanks in advance,
pbg