This article provides a resolution for when the messenger button is not appearing properly.
This issue occurs if the messenger is not configured properly or there are unfinished configuration settings.
If your messenger is not shown properly (e.g. the button is not shown), it means that your chat is not loading due to an unfinished configuration in Admin > Messenger > Configuration.
Please go through all the steps for Customizing and enabling Kayako Messenger and make sure you fill in all the fields of the messenger configuration wizard. Then, save the changes.