Thanks for the hint, Piero! Indeed, I got further in the install process this time (/e/ is currently being installed as I write these lines).
Indeed, I wasn’t quick enough to get to the recovery mode.
Note for future users running into the same problem: You have to really press PWR + Bixby+Vol down and then IMMEDIATELY after, PWR + bixby + vol U to get to Teamwin. waiting even half a second is way to much. we’re talking about 0,1 to 0.3 seconds (approx).
== PROBLEM SOLVED ==
cheers
Denis