No problem, happy to help.
I still can't access your public share link so I'm guessing at how your build is structured, but from the looks of your preview I'd say you added a button to the dynamic list element for your blog post grid?
If so, one way to do it is from in the designer view - click on any one of the summaries to select it, then in the right hand navigator tab click on the item that is your button. It might just show up as 'Link'. On your design you should now see the button of the summary you selected showing up with the blue label 'Link' or something above it and a little white settings wheel displayed.
Click the settings wheel and you should get some link options in a little panel that looks like below...
It might default to show you the first icon options which is for external URLs. You don't want that, so choose the next icon along that looks like a purple page in my screenshot. Thats the options which allow you to access what they call a 'collection detail page' - in plain english your blog post.
From the purple dropdown that says "Choose a detail page" just select the 'Current...' option and then when you preview you should find that hey presto you can link to the main blog post.
Let me know if that works or see if you can send your public share link through and I can take a look further.