Hi,
The easiest way will be to redirect to a specific page instead of hiding the button.
For that, you can edit the view "order / listing" and add this code at the top:
Code:
<?php
if(empty($this->rows)){
$app = JFactory::getApplication;
$app->redirect('your_url');
}
?>
For the checkout, the view to edit is "checkout / step".
http://www.hikashop.com/support/support/documentation/153-customize-the-display.html
