Switching to unstable seems to break the beta 5 installation after updating.
The brightness is set to 100 which makes the display black and after setting it back one can see that the de is stuck at the boot/kde logo with functional touchscreen (pointer is moving). For login all passwords user/kde/root need to be reseted and after trying to restart plamo with startplasma-wayland, kwin complains about a symbolerror for libkwayland.