Simple form submit button not working - ruby-on-rails-4

Question

somehow my form is not working and I dont know why. Heres my code:
<%= simple_form_for #cr, url: edit_cr_path do |f| %>
<hr>
Design Office Involvements<br>
<%= f.collection_check_boxes :design_office_ids, DesignOffice.all, :id, :sub, {:item_wrapper_class => 'checkbox_container'} %>
<hr>
Procurement Involvements<br>
<%= f.collection_check_boxes :procurement_ids, Procurement.all, :id, :sub, {:item_wrapper_class => 'checkbox_container'} %>
<hr>
Installation Involvements<br>
<%= f.collection_check_boxes :installation_ids, Installation.all, :id, :sub, {:item_wrapper_class => 'checkbox_container'} %>
<hr>
<div class="row">
<div class="col-md-6">
Assessment Status
<%= f.input :assessment_status, :collection => [['Impacted','Impacted'],['Not impacted','Not impacted'],['Under assessment','Under assessment'],['New','New']], label: false, selected: ['New', 'New'] %>
</div>
<div class="col-md-6">
<div style="float: right">
<%= f.button :submit, 'Save' %>
</div>
</div>
</div>
<br>
<% end %>
Controller methods looking like this:
class CrsController < ApplicationController
def edit
#cr = Cr.find(params[:id])
end
def update
#cr = Cr.find(params[:id])
#cr.update_attributes(cr_params)
redirect_to edit_cr_path(#cr)
end
private
def cr_params
params.require(:user).permit(:id, :assessment_status)
end
end
And routes like this:
EndToEndManagement::Application.routes.draw do
get '/cr/:id', :to => 'crs#edit', :as => 'edit_cr'
put '/cr/:id', :to => 'crs#update'
patch '/cr/:id', :to => 'crs#update'
end
And thats the html code rails makes of my submit button:
<div class="col-md-6">
<div style="float: right">
<input class="btn" name="commit" type="submit" value="Save" />
</div>
</div>
I think the submit button is not correctly attached to the form but I tried to move it and clear some divs but nothing worked.
Best regards.
EDIT:
Thats what I tested
Removed my routes in routes.rb and replaced it with resources :crs and changed my first line in the form to <%= simple_form_for #cr do |f| %>. Didnt work!
Changed my simple_form to normal form. Didnt work!
Wrote a whole testapp with a scaffold and this form an it worked but I dont know why so I added part by part to my actual app and nothing made it working.

Answer 1

Found my mistake! Not that it would be so mind blowing but I will still post it :D
Had this small mistake in my application.html.erb
<div style="font-size: 1.3em"
<%= yield %>
</div>
Changed it to:
<div style="font-size: 1.3em">
<%= yield %>
</div>
And now it works fine.

Answer 2

It does not seem as edit_cr_path is the right url to go when you're trying to save a form.
You'll need another route:
post '/crs', :to => 'crs#create'
In your view, you probably won't need the url option as Rails can infer just looking at the object.
<%= simple_form_for #cr do |f| %>
But your object needs to be a new instance coming from your controller:
class CrsController < ApplicationController
def new
#cr = Cr.new #or whatever else to initialize the object
end
def create
#save the instance here
end