Static news page has for thumbnail the featured image of the first posts

the_post_thumnbail() doesn’t accept an arbitrary post id as an argument. It just takes a size to display. To get the post thumbnail URL of a given post, you need to use get_the_post_thimbnail_url():

<?php echo get_the_post_thumbnail_url( get_option( 'page_for_posts' ), 'full' ); ?>

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)