Sharepoint 2013 not recognizing new custom login page

I've been tasked with updating our custom login page to send the user to a specific URL when clicking the login button. Here are the steps I took:

Updated the button in Visual Studio to redirect to the new URL.
Deployed the solution from VS.
Did an iisreset for good measure.
The change did not take. The button still takes the user to the old location/landing page.

Then tried these steps:

Created a brand new Sharepoint solution under a different name in VS and added a simple aspx page with a single button pointing to the new URL we want.
Deployed the solution from VS.
Went into the Default authentication provider and updated the Custom Sign In Page URL to the page in my new solution.
Did an iisreset.
Still, the old login page displays.

I then went as far as uninstalling and removing the old custom login page completely. Now I get the typical resource not found error:

Can someone please tell me how/why it is still pointing to my old page even though I updated the custom sign in page in the authentication provider settings to point to my new page??? Is there a setting somewhere else that needs to be updated as well?