Cannot start Ghost

Debug Information:
OS: Ubuntu, v18.04.3 LTS
Node Version: v10.16.3
Ghost Version: 3.5.1
Ghost-CLI Version: 1.13.1
Environment: production
Command: ‘ghost start’

+ sudo systemctl reset-failed ghost_site-com
✔ Ensuring user is not logged in as ghost user
✔ Checking if logged in user is directory owner
✔ Checking current folder permissions
+ sudo systemctl is-active ghost_site-com
✔ Validating config
✔ Checking folder permissions
✔ Checking file permissions
✔ Checking content folder ownership
✔ Checking memory availability
✔ Checking binary dependencies
+ sudo systemctl start ghost_site-com
+ sudo systemctl stop ghost_site-com
✖ Starting Ghost: site-com
A GhostError occurred.

Message: ER_ACCESS_DENIED_ERROR: Access denied for user 'ghost'@'localhost' (using password: YES)
Help: Unknown database error
Suggestion: journalctl -u ghost_site-com -n 50

Running the suggestion doesn’t do anything, says no journal files are found.

I’ve been having trouble with Ghost since trying to update to the latest version, then I couldn’t start Ghost, so I rebuilt the droplet and tried again. Ghost started up fine, then I used ghost restart after updating the config for mail and a content adapter, it won’t start again because of this error.