How to redirect WordPress home page to custom static HTML page

This code may help resolve the issue for this particular situation. Put this code in yor theme’s functions.php.

add_action('template_redirect', 'default_page');
function default_page(){
    if(is_home() or is_front_page()){
       exit( wp_redirect("http://path/to/your/html/file"));
    }
}

Replace http://path/to/your/html/file to exact url of html file.

I hope this helps.