Please find the details why MariaDB does not start in /var/log/syslog, e.g.
# grep mariadb /var/log/syslog
Normally you'll find a detailed explanation there why the database server won't start.
Thanks for your time, here is my record
Jul 11 14:22:01 brave-wozniak systemd[1]: mariadb.service: Found left-over proce ss 1511 (mysqld) in control group while starting unit. Ignoring.
Jul 11 14:22:01 brave-wozniak systemd[1]: mariadb.service: Will not start SendSI GKILL=no service of type KillMode=control-group or mixed while processes exist
Jul 11 14:22:01 brave-wozniak systemd[1]: mariadb.service: Failed to run 'start- pre' task: Device or resource busy
Jul 11 14:22:01 brave-wozniak systemd[1]: mariadb.service: Failed with result 'r esources'.
Jul 11 14:22:06 brave-wozniak systemd[1]: mariadb.service: Found left-over proce ss 1511 (mysqld) in control group while starting unit. Ignoring.
Jul 11 14:22:06 brave-wozniak systemd[1]: mariadb.service: Will not start SendSI GKILL=no service of type KillMode=control-group or mixed while processes exist
Jul 11 14:22:06 brave-wozniak systemd[1]: mariadb.service: Failed to run 'start- pre' task: Device or resource busy
Jul 11 14:22:06 brave-wozniak systemd[1]: mariadb.service: Failed with result 'r esources'.
Jul 11 14:22:11 brave-wozniak systemd[1]: mariadb.service: Found left-over proce ss 1511 (mysqld) in control group while starting unit. Ignoring.
Jul 11 14:22:11 brave-wozniak systemd[1]: mariadb.service: Will not start SendSI GKILL=no service of type KillMode=control-group or mixed while processes exist
Jul 11 14:22:11 brave-wozniak systemd[1]: mariadb.service: Failed to run 'start- pre' task: Device or resource busy
Jul 11 14:22:11 brave-wozniak systemd[1]: mariadb.service: Failed with result 'r esources'.
Jul 11 14:22:14 brave-wozniak systemd[1]: mariadb.service: Got notification mess age from PID 1511, but reception only permitted for main PID which is currently not known