Please check if you're using any plugins from other vendors. These may interfere with Linchpin Theme and cause the configuration site to be disabled. Please deactivate other plugins in order to see if this is the case.
However, if the configuration site is still not shown properly, please contact our support: email@example.com.
If these tips do not fit to your layout or if they are positioned wrong the only actual workaround is to deactivate this Confluence feature. To do this just find the Confluence Dashboard Plugin and disable the module "Onboarding Dialog" as you can see here:
First of all: Please make sure that all character encodings are set to UTF-8 as Atlassian recommends. Linchpin Theme does not properly work with other encodings, especially the theme configuration will assuredly break sometime.
If you do not reach the configuration dialog any more, the theme looks broken and maybe the memory usage on your server increases rapidly when you try to reach the Linchpin Theme administration please contact our support team and provide the following information from your database:
SELECT * FROM BANDANA WHERE BANDANAKEY = 'net.seibertmedia.confluence.plugins.linchpin-theme:build';
SELECT * FROM BANDANA WHERE BANDANAKEY = 'net.seibertmedia.confluence.linchpin.theme.config';
SELECT * FROM BANDANA WHERE BANDANACONTEXT = 'net.seibertmedia.confluence.plugins.theme.footer.config';
Add a support zip as well so we can have a look at your logfiles.
Side notes: If your database reports heavy memory usage while working on the requests (or maybe just stops the requests after a while) we recommend to uninstall Linchpin Theme and delete (only!) these 3 database entries by hand. Hence your theme configuration will be deleted you can install Linchpin Theme again with a clean configuration.
If you have a fully configured and running second system (e.g. for test purposes) you can try to export theme configuration from there and import it to the broken system.