Comment 2 for bug 1879155

Thank you for taking the time to file a bug report.

Per your console log:

Renaming removed key_buffer and myisam-recover options (if present)
Initialization of mysqld failed: 0
Warning: Unable to start the server. Please restart MySQL and run mysql_upgrade to ensure the database is ready for use.
/var/lib/mysql/ibdata1: 30680
ERROR: Database files are locked. Daemon already running?
Warning: Unable to start the server.
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.
invoke-rc.d: initscript mysql, action "start" failed.

It looks that previous database process (the existing/installed one) hasn't shutdown correctly and it is still holding a lock for the database file. Make sure you kill existing previous databases processes and try again re-starting the mysql service.

Since it seems likely to me that this is a local configuration problem,
rather than a bug in Ubuntu, I am marking this bug as 'Incomplete'.

However, if you believe that this is really a bug in Ubuntu, then we would
be grateful if you would provide a more complete description of the problem
with steps to reproduce, explain why you believe this is a bug in Ubuntu
rather than a problem specific to your system, and then change the bug
status back to "New".

For local configuration issues, you can find assistance here:
http://www.ubuntu.com/support/community