HA OS on Odroid M1 only boots with recovery button pressed

Hello everybody,
I have an Odroid M1 and wanted now to setup Homeassistant OS on that board.
After a battle to get the petitboot version upgraded to 20230328 I flashed my eMMC card and inserted it into the M1 board.
The problem is that HA will only start with the recovery button pressed on the board and obviously I want to get rid of that! Can anyone point me into the right direction on how to achieve that?
I have read through this documentation and stumbled around this paragraph in the Technical note section:

The Home Assistant OS image is bootable by the SoC directly. This means that no help from the Hardkernel provided and pre-installed bootloader Petitboot is necessary. However, the ODROID-M1 automatically boots from internal SPI. To boot directly off the SD-card or eMMC you need to press the recovery button.

The SPI flashed U-Boot SPL tries searches for an U-Boot binary on the SD-card (and from eMMC with Petitboot 20230328 and later). This mechanism allows you to boot the Home Assistant OS U-Boot without pressing the recovery button.

But honest to say I do not know what that actually means.

Thanks for your help