I just installed netrunner 14 to a used drive which had a user in it ( and was kept ).
When I try to login in with the correct password the screen goes blank for a few seconds then returns.
When I try to login with the wrong password. The wrong password stays there so that I can change it.
So it looks to me that it is recognizing the correct password but will not go any further.
Yea. there must be a configuration sitting or file somewhere in that user directory preventing plasma from loading, try logging in to a VT (CNTRL+ALT+F1), and delete the ~.kde directory hidden in your home folder, then switch back to your GUI terminal (ALT+F7) and log in.
There must have been more than just the permission for the .kde folder
I tried to use the netrunner live disk and sudo dolphin and change the permission for all of the hidden folders but that didn’t work so I started another distro and changed the permission with gnome-commander and that worked ( it’s the most reliable gui for changing permissions )