How to install bootstrap in child theme

by

get_template_directory_uri always returns the parent theme’s URI.

From the docs:

In the event a child theme is being used, the parent theme directory URI will be returned

You probably want get_stylesheet_directory_uri.

add_action('wp_enqueue_scripts', 'wpse174502_styles', PHP_INT_MAX);
function wpse174502_styles()
{
    wp_enqueue_script('bootstrap-js', get_stylesheet_directory_uri().'/bootstrap/js/bootstrap.min.js', array('jquery'), NULL, true);
    wp_enqueue_style('bootstrap-css', get_stylesheet_directory_uri().'/bootstrap/css/bootstrap.min.css', false, NULL, 'all');
}

Whenever you’re debugging enqueues be sure to…

  1. Check the rendered page source. are the assets you expected being included?
  2. Check the developer tools console in your browser of choice. Are there errors? Are those errors related to your assets?