Reset WP Engine file permissions on the site itself. Requires WPE API to be active for specified account.

wpe_reset_file_permissions.php

<?php

/**
 * Rset file permissions on a WPE customer site (without signing-in to a dashboard)
 * 
 * Adapted from the WPE mu-plugin present on all customer sites, at
 * `wp-content/mu-plugins/wpengine-common/admin-ui.php`
 */

// Simply hit this hook URL in your desired context:
$url = "https://api.wpengine.com/1.2/?method=file-permissions&account_name=" . $wpe_account_username . "&wpe_apikey=" . $wpe_api_key;