First, let's check if MySQL is running. For that, access your instance via SSH and execute:
sudo /opt/bitnami/ctlscript.sh status mysql
If it is stopped, start it:
sudo /opt/bitnami/ctlscript.sh start mysql
Then, we should check if you are able to access mysql via command line. For that, execute this command:
sudo /opt/bitnami/mysql/bin/mysql -uroot -pPASSWORD
PASSWORD needs to be changed with your MySQL root password.
Please confirm if the steps below worked properly for you.