to connect to a Database in custo diagnostic 5.XX you need to have a download SQuirreL SQL Client, you can do so from the following LINK
Now switch off the Apache Tomcat diagserver from the Services menu in Windows
Start the SQuirrel SQL Client and enter the settings to connect to the database
The DbUrl can be found in the following file on the following location : C:\Program Files\custo diagnostic server\conf\diag.properties
now you can open the database and look into it
For a more detailed instruction look into this VIDEO