Launch Wordpress Site from index

Launch Wordpress Site from index

I'm trying to launch a wordpress website from a non wordpress static home
page (index.html) using a button.
The index.html will provide users an option to leave me their email
contact info or redirect them to the wordpress site I have created when
they click the "Enter" button.
The wordpress site works fine when the standard wordpress index.php file
is located in the site root. When I replace this file with my own
index.html file (with the button and contact code), I can't get the
wordpress index.php file to launch. I renamed the original wordpress
index.php to indexWP.php and I call that file from my new index.html file
using the code suggestion here: A button to start php script, how?
<form action="indexwp.php" method="get">
<input type="submit" value="Enter">
</form>
When I use the above, it gives me a 404 Page Not Found error when I click
Enter.
The original Wordpress index.php looks like this (renamed to indexwp.php):
<?php
/**
* Front to the WordPress application. This file doesn't do anything, but
loads
* wp-blog-header.php which does and tells WordPress to load the theme.
*
* @package WordPress
*/
/**
* Tells WordPress to load the WordPress theme and output it.
*
* @var bool
*/
define('WP_USE_THEMES', true);
/** Loads the WordPress Environment and Template */
require('./wp-blog-header.php');
I'm a noob so I suspect it's something I'm misinterpreting with the above
sample code.