the jQuery(".open_fancybox").click() should be also INSIDE the jQuery(document).ready() method
additionally, you are nesting a jQuery(document).ready() method inside another like
jQuery(document).ready()
function() {
jQuery('.fancybox').fancybox();
jQuery(document).ready(function() {...
you functions should be like
jQuery(document).ready(function(){
jQuery(".fancybox-buttons").fancybox({
// fancyboxAPI options here
}); // first fancybox
jQuery(".open_fancybox").click(function() {
jQuery.fancybox.open(
[// group of images],
{
// fancybox API options here
}
); // second fancybox
}); // click
}); //ready