M5StickCplus can't flash UIflow2 Firmware

[sirtet]

I use M5Burner 202505131800
Flashing fails with different symptoms:

Maybe a year ago or more i had tried, and it always finisthed after an abnormally fast flash-progress (2-3sec.) with a success message, but then never showed anything on display, looked like dead.
I could always return to UIFlow 1 Versions.

Now i tried again, and after a few fails it worked one time, i saw the new UI. But i could not connect.
So i flashed again with an older Version, 2.3.0 i think.
But now the screen was black again. Pushing buttons plays the different pitch beeps, and the screen shows some of the elements:

I have two of the sticks, same issue with both...
Again, i can return to UIFlow1, but no luck with UIFlow2.
I tried multiple erases before flashing too, no change.

Is this a known issue? Any ideas to fix it?