How do I address the checkout button? I need to add a custom function to the Confirm Order button on a Commerce Checkout form. I can't figure out how to call it. The button ID is #edit-continue and its displayed text is Confirm Order. I thought this would show up in the $form[submit] array, but that array is empty. So I checked $form['buttons']['continue']['#submit'], which  seems to be where Drupal Commerce stores the submit functions.
I created a module and two functions.
function MYMODULE_form_commerce_checkout_form_checkout_alter($form, $form_state, $form_id){ 
   drupal_set_message('ALTERING CHECKING OUT! THIS WORKS' . $form_id);   
   $form['buttons']['continue']['#value'] = 'Send Me A Quote!';
   $form['buttons']['continue']['#submit'][] = 'MYMODULE_submit';       

function MYMODULE_submit_function($form, &amp;$form_state) {
  die('Triggered submit');
}

drupal_set_message() shows the message, but the submit function isn't invoked, and the text in the button is not altered. So clearly, the problem is that I am not targeting the button properly. How do I &quot;address&quot; that button?
To make it clearer, I need to overload that button, not replace the commerce checkout functionality.
PS: I have no access to the console or Devel. So I'm limited to debugging with var_dump().
Your changes to $form here are lost because you are passing by value.  Pass by reference using &amp;$form instead:

function MYMODULE_form_commerce_checkout_form_checkout_alter(&amp;$form, &amp;$form_state, $form_id) {