Ok, sorry if my post is so confused, I thinck it si because the system went confused.
So first i have made my installation of Lx 4.1 with the live disc.
Then it has worked well some weeks.
I needed to install some tools and i did upgrade Lx like I am used to (that is my mistake) instead of discover.
Since this last installation I no longer got the connexion screen sddm.
I have tried some commands found in the post failure-to-load-login-screen-please-help
wich gave no successfull results
I tried to downgrade with the command:
sudo dnf clean all && sudo dnf downgrade sddm
I can’t explain why it has used à cooked or rolling rpm instead of rock (may be i have made a wrong selection).
The result is what you had sayed: no upgrade or downgrade is possible.
Most of my trial were done on sunday but mirrors were unreachable.
I hope my post is less confused.
Finaly I already had tried to make a new install of Lx 4.1 from the live mandriva one usb but it is blocked when choosing the partition: from this point nothing is possible except cancel. Like it has detected a previous installation of Lx4.1 and didn’t want to overwrite it.
Do you think it will work with the link you have given me ?