OpenCart Square Payment Extension Fix

Project Title: Fix Square Payment Extension (iSenseLabs) on OpenCart 2.0.3.1

Project Overview I am looking for an experienced OpenCart developer to troubleshoot and fix a specific issue with the Square Payments extension (developed by iSenseLabs) on a legacy OpenCart installation (Version 2.0.3.1).

Background & Current Status

-->> Platform: OpenCart 2.0.3.1
-->> Extension: Square Payments by iSenseLabs (Note: Support for this extension has been discontinued by the vendor).
-->> Status: The extension has been successfully uploaded via cPanel and configured in the Admin panel. The API connection to Square is established and authorized. All settings have been enabled for relevant zones/geographies.

The Issue While the payment method appears correctly on the checkout page, the integration fails during the final selection step:

-->> The customer selects "Debit/Credit Card" (Square) as the payment method.
-->> The interface attempts to load the card input fields but gets stuck in a perpetual "Loading" state.
-->> The actual fields to enter card details never render.

Requirement I need an expert to debug the frontend/AJAX issue preventing the card fields from loading. Since the vendor support is discontinued, you must be comfortable debugging the existing code, checking for JavaScript conflicts, or fixing API callback issues manually.

Deliverables

-->> Diagnosis of the specific conflict or error (likely JS/AJAX related).
-->> A fully functional checkout experience where card fields load, and payments are processed successfully.

If extra module updates or Square settings are advisable, include those recommendations in your hand-off notes.