Did your syslog contain any line similar to these?

/etc/mysql/debian-start[3138]: Upgrading MySQL tables if necessary.
/etc/mysql/debian-start[3141]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored
/etc/mysql/debian-start[3141]: Looking for 'mysql' as: /usr/bin/mysql
/etc/mysql/debian-start[3141]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck
/etc/mysql/debian-start[3141]: This installation of MySQL is already upgraded to 10.0.9-MariaDB, use --force if you still need to run mysql_upgrade
/etc/mysql/debian-start[3152]: Checking for insecure root accounts.
/etc/mysql/debian-start[3157]: Triggering myisam-recover for all MyISAM tables
/etc/mysql/debian-start[3719]: Upgrading MySQL tables if necessary.
/etc/mysql/debian-start[3722]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored
/etc/mysql/debian-start[3722]: Looking for 'mysql' as: /usr/bin/mysql
/etc/mysql/debian-start[3722]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck
/etc/mysql/debian-start[3722]: This installation of MySQL is already upgraded to 10.0.9-MariaDB, use --force if you still need to run mysql_upgrade
/etc/mysql/debian-start[3733]: Checking for insecure root accounts.
/etc/mysql/debian-start[3738]: Triggering myisam-recover for all MyISAM tables
mysqld_safe[5671]: 
mysqld_safe[5671]: Installation of system tables failed!  Examine the logs in
mysqld_safe[5671]: /var/lib/mysql for more information.
mysqld_safe[5671]: 
mysqld_safe[5671]: The problem could be conflicting information in an external
mysqld_safe[5671]: my.cnf files. You can ignore these by doing:
mysqld_safe[5671]: 
mysqld_safe[5671]:     shell> /usr/scripts/scripts/mysql_install_db --defaults-file=~/.my.cnf
mysqld_safe[5671]: 
mysqld_safe[5671]: You can also try to start the mysqld daemon with:
mysqld_safe[5671]: 
mysqld_safe[5671]:     shell> /usr/sbin/mysqld --skip-grant --general-log &
mysqld_safe[5671]: 
mysqld_safe[5671]: and use the command line tool /usr/bin/mysql
mysqld_safe[5671]: to connect to the mysql database and look at the grant tables:
mysqld_safe[5671]: 
mysqld_safe[5671]:     shell> /usr/bin/mysql -u root mysql
mysqld_safe[5671]:     mysql> show tables
mysqld_safe[5671]: 
mysqld_safe[5671]: Try 'mysqld --help' if you have problems with paths.  Using
mysqld_safe[5671]: --general-log gives you a log in /var/lib/mysql that may be helpful.
mysqld_safe[5671]: 
mysqld_safe[5671]: The latest information about mysql_install_db is available at
mysqld_safe[5671]: https://mariadb.com/kb/en/installing-system-tables-mysql_install_db
mysqld_safe[5671]: MariaDB is hosted on launchpad; You can find the latest source and
mysqld_safe[5671]: email lists at http://launchpad.net/maria
mysqld_safe[5671]: 
mysqld_safe[5671]: Please check all of the above before submitting a bug report
mysqld_safe[5671]: at http://mariadb.org/jira
mysqld_safe[5671]: 
/etc/init.d/mysql[6513]: 0 processes alive and '/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf ping' resulted in
/etc/init.d/mysql[6513]: #007/usr/bin/mysqladmin: connect to server at 'localhost' failed
/etc/init.d/mysql[6513]: error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)'
/etc/init.d/mysql[6513]: Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists!
/etc/init.d/mysql[6513]: