Alright, here is your `page-blog-grid.php` file with the `the_post_thumbnail()` calls updated to use the `'square_1000'` image size.
I've identified and changed all three instances where `'egns-thumb-cart'` was being used for the post thumbnail within the different demo sections.
**Important Reminders:**
* **You MUST still add `add_image_size('square_1000', 1000, 1000, true);` to your `helpers/theme_setup.php` file.** This PHP file only calls the size; WordPress needs to know how to generate it.
* **You MUST Regenerate Thumbnails** after modifying `theme_setup.php` to create the new image size for existing posts.
* **Clear all caches** (WordPress caching plugins, server-side caching, browser cache) after making these changes.
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```php
Blog Grid - GeekySaint
