So if I understand you correctly:
You want to show a modal after clicking on submit (which is not a submit button) that shows all the data and a real submit button?
If that’s the case, create a modal and place the form inside it. Only that form, it’ll be the only one.
When you click on the first button (set type to normal) set a dynamic event that links the inputs of your form (of the modal) with the inputs of your main page, and after all those bindings, show the modal, be sure you have a submit button ON the form like Tasos says.
Also you say that you have an error, have you tried to enable debug mode and see what is exactly the error you have?