Screen turn black and only mouse cursor

Do you spot any error in ~/.local/share/sddm/wayland-session.log ?

here is what it says

                                                                         
kdeinit5: preparing to launch '/usr/lib/kf5/klauncher'
kdeinit5: Launched KLauncher, pid = 1434, result = 0
No backend specified through command line argument, trying auto resolution
kwin_xkbcommon: XKB: inet:334:58: unrecognized keysym "XF86EmojiPicker"
(WW) Option "-listen" for file descriptors is deprecated
Please use "-listenfd" instead.
(WW) Option "-listen" for file descriptors is deprecated
Please use "-listenfd" instead.
qml: FORCE-BLUR: starting the script
qml: ["yakuake","urxvt","keepassxc"]
js: KWinMax2NewVirtualDesktop: Handler installed
kdeinit5: opened connection to :1
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Unsupported maximum keycode 708, clipping.
>                   X11 cannot support keycodes above 255.
Errors from xkbcomp are not fatal to the X server
Initializing  "/usr/lib/qt/plugins/plasma/kcms/systemsettings/kcm_mouse.so"
Initializing  "/usr/lib/qt/plugins/plasma/kcms/systemsettings/kcm_style.so"
kdeinit5: Got SETENV 'GTK_RC_FILES=/etc/gtk/gtkrc:/home/solidus/.gtkrc:/home/solidus/.config/gtkrc' from launcher.
kdeinit5: Got SETENV 'GTK2_RC_FILES=/etc/gtk-2.0/gtkrc:/home/solidus/.gtkrc-2.0:/home/solidus/.config/gtkrc-2.0' from launcher.
QDBusConnection: error: could not send signal to service "" path "//home/solidus/.kde4/share/config/kdeglobals" interface "org.kde.kconfig.notify" member "ConfigChanged": Invalid object path: //home/solidu>
Initializing  "/usr/lib/qt/plugins/plasma/kcms/systemsettings/kcm_fonts.so"
org.kde.plasma.session: process job  "kcminit_startup" finished with exit code  0
Qt: Session management error: networkIdsList argument is NULL
kdeinit5: Got SETENV 'SESSION_MANAGER=local/evie-dev:@/tmp/.ICE-unix/1615,unix/evie-dev:/tmp/.ICE-unix/1615' from launcher.
kdeinit5: Got SETENV 'SESSION_MANAGER=local/evie-dev:@/tmp/.ICE-unix/1615,unix/evie-dev:/tmp/.ICE-unix/1615' from launcher.
Initializing  "/usr/lib/qt/plugins/plasma/kcms/systemsettings/kcm_kgamma.so"
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/kaccess.desktop" ("/usr/bin/kaccess")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/powerdevil.desktop" ("/usr/lib/org_kde_powerdevil")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/polkit-kde-authentication-agent-1.desktop" ("/usr/lib/polkit-kde-authentication-agent-1")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/pam_kwallet_init.desktop" ("/usr/lib/pam_kwallet_init")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/xembedsniproxy.desktop" ("/usr/bin/xembedsniproxy")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/org.kde.plasmashell.desktop" ("/usr/bin/plasmashell")
Initializing  "/usr/lib/qt/plugins/plasma/kcms/systemsettings/kcm_touchpad.so"
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/baloo_file.desktop" ("/usr/lib/baloo_file")
Xlib XKB extension major= 1  minor= 0
Installing the delayed initialization callback.
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/gmenudbusmenuproxy.desktop" ("/usr/bin/gmenudbusmenuproxy")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/pulseaudio.desktop" ("/usr/bin/start-pulseaudio-x11")
New PolkitAgentListener  0x557ab1924ec0
Adding new listener  PolkitQt1::Agent::Listener(0x557ab19bdbc0) for  0x557ab1924ec0
Listener online
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/org.kde.kdeconnect.daemon.desktop" ("/usr/lib/kdeconnectd")
org.kde.plasma.session: Starting autostart service  "/home/solidus/.config/autostart/ulauncher.desktop" ("/usr/bin/env", "GDK_BACKEND=x11", "/usr/bin/ulauncher", "--hide-window", "--hide-window")
org.kde.plasma.session: Starting autostart service  "/home/solidus/.config/autostart/org.moson.matray.desktop" ("/usr/bin/matray", "--delay")
Authentication agent result: true
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/xapp-sn-watcher.desktop" ("/usr/lib/xapps/sn-watcher/xapp-sn-watcher")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/snap-userd-autostart.desktop" ("/bin/snap", "userd", "--autostart")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/msm_kde_notifier.desktop" ("/usr/bin/msm_kde_notifier")
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/pamac-tray-plasma.desktop" ("/usr/bin/pamac-tray-plasma")
org.kde.plasma.session: Starting autostart service  "/home/solidus/.config/autostart/org.kde.latte-dock.desktop" ("/usr/bin/latte-dock")
X server XKB extension major= 1  minor= 0
org.kde.plasma.session: Starting autostart service  "/etc/xdg/autostart/geoclue-demo-agent.desktop" ("/usr/lib/geoclue-2.0/demos/agent")




Shot in the dark.

When you get to the part where you have a working mouse cursor, wait about 30 seconds then press (all together):

ALT + SHIFT + F12