Trouble installing bullseye on Rock Pi 4 A

[Christian Kastner <ckk@debian.org>]

Hi,

For some reason, I'm not getting a signal via HDMI when running the
bullseye installer from the prepared SD card images. I thought this
might be a monitor issue, but booting a microSD card with the
manufacturer's image shows that this is not the case.

Any ideas what could be going on? There's an eMMC attached, but knowing
that it might affect the boot process, I have zeroed it out.

I'm doubtful that it's the installer. Yesterday, I finished an
installation on a RockPro64, a similar platform, without issues.

I'd attach a serial cable but the Rock Pi 4 requires on capable of
1.5Mbps and none of my cables are. I thought I'd ask here before
purchasing one.

Best,
Christian