Thanks for your replies guys. I tried another SD Card, downloaded the image again, extract it before burning but nothing helps. Luckily a friend of mine has a raspi 3B as well and he had still the recalbox 4.0 on it. I made a image of his sd card and burned it on my sd card, and what to say, it works like a charm. Lessons learned, next time i wanna try a new version, i make a backup of the old one first 🙂
