On the mainboard is a 2×3 6-pin header with a jumper where one of the center pin is missing.
D3543A1xAdminpackageCompressedFlashFiles_V50013R1140_1302609.ZIP1c6b6acd8520d54f5e3ff8fa8030b7340c242ce051e065b16a13581e5b131125In the BIOS one can configure the BIOS to expose itself via the COM1 serial console instead of one of the Display Port outputs.
We found out that it is not possible to boot from a USB stick while the BIOS is redirected to the serial console.