1- start the live cd
2- download the main.py file from this link
https://www.swisstransfer.com/d/afe0759f-39f6-4620-95e7-d9e87a5c3d19
3 - open the terminal and run dolphin with this command
sudo pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY KDE_SESSION_VERSION=5 KDE_FULL_SESSION=true dbus-launch dolphin
4 - Navigate to the folder
/usr/lib/x86_64-linux-gnu/calamares/modules/networkcfg/
and delete the main.py file and paste the main.py file that you downloaded at the place
5 - Log out of the account
6 - disconnect from the internet
7 - install your kde neon Good Luck 
