Most likely you forgot the new url or it is not like you defined earlier. Please send me your phpmyadmin panel login information via private message. I will do a reset for you and then change the admin path to "PPpAA23wTiSvwfm" and we will see the situation together.
The definition you add should be under the [mysqld] line. If your file does not contain the line [mysqld], you can add it manually.
Please define as below. If possible, edit and save the "/etc/mysql/my.cnf" file after SSH login with Filezilla.