So here I am again, me and my mythtv battle

On my old Mageia 8 there was some mythtv backend and mythtv frontend that never came to work after a hard drive died and too bad a backup around mythtv.
I now have done an upgrade from Mageia 8 to Mageia 9 (Simple upgrade).
I found remnants of the old mythtv i.a. here: /var/lib/mysql/mysql. The files here were moved but that meant I couldn't start mysqld. Then, in my panic, I tried running mysql_install_db (as root). It was not a success either.
My 300 home videos are under control, so now I would like to start from scratch with a fresh installation of mythtv.
Does anyone know which folders, files and config files need to be deleted so that nothing remains from the old mythtv ?
Have plowed through the wiki without finding a clear procedure for installing mythtv.
You probably start by installing packages covering mariadb, myth-backend and perhaps mythtv-setup.
So what do I then do, I can't figure out how "mysql -u root -p < /usr/share/mythtv/initialdb/mc.sql", "mythtv-setup" and "mysql_install_db" work together, what exactly should I do ?
Hope someone can help with a clean mythtv install

Good weekend to all.
Best regards
Anders