The display manager SDDM is normally installed when KDE is selected, so the best way forward is to find out what’s preventing it from starting. Knowing some detail about your Intel and NVidia GPUs and other hardware should help with diagnosis. I suggest to boot without nomodeset on cmdline into multi-user mode by appending a space and 3 on the kernel cmdline along with adding plymouth.enable=0 and nouveau.modeset=0 and removing quiet and splash=silent. As boot completes, try to make a mental note of error messages seen on screen. When boot completes, do Ctrl-Alt-F3, login as root, run ‘zypper in inxi’, then run ‘WINDOWMANAGER=startplasma-x11 startx’. If that fails to start Plasma, then try ‘WINDOWMANAGER=startkde startx’. If you get into Plasma, open Konsole and do:
**cat /proc/cmdline
inxi -GxxS
xrandr --listproviders
xrandr**
Copy all that input and output to a file, then exit Plasma. Next, paste that file’s content here, upload /var/log/Xorg.0.log to https://susepaste.org, and report the resultant URL here. Sometimes the command susepaste will successfully do the uploading, so you can avoid transferring the info elsewhere to use a web browser for uploading, e.g.
**susepaste -n SceoMyntan -e 10080 /var/log/Xorg.0.log
susepaste -n SceoMyntan -e 10080 mycatinxixrandrifile**
If startx even fails as root login, then try uploading /var/log/Xorg.0.log anyway. Also do:
**dmesg > dmesgfile.txt
journalctl -b > jrnlfile.txt
lspci -nnk | grep -A4 VGA > other.txt
rpm -qa | grep dm >> other.txt**
and upload files dmesgfile.txt, jrnlfile.txt and other.txt to susepaste.org. Report here whatever you can remember of error messages seen on screen during boot.