First, did you check your LAMP configuration ? Try to access a static HTML page with images, then a simple php script.
If it’s ok, then try to disable any plugin, mu-plugin and use a native wordpress them (such as twentyseventenn). You can also turn debug on in wp-config.php
define('WP_DEBUG', true);
define('WP_DEBUG_DISPLAY', true);
to display php error in the UI. Perhaps it could help to find the issue.