Hello @Mario_Marietto
It is the key on Edge-V, middle of the three keys.
- Write image [1] to SD card
- Insert the SD card to Edge-V
- Press FUNC key three times to boot from the SD card.
It works on my side.
[1] - https://dl.khadas.com/products/oowow/images/edge/edge-freebsd-aarch64-13.0-release-20210613.img.xz