Laravel PayPal Integration Task

Attached are the codes I have written to submit my shopping cart details to paypal. Attached is my laravel and paypal log. There are two problems, one is message malformed and the other is error 400 when access paypal sandbox. This is a simple troubleshooting and fixing task for someone who has experience and this does not involve rocket science. Please take note that the task should be completed via teamviewer only. I can't share codes which I created over 6 months for your pleasure. Pricing is fix and not negotiable, that is final. Think long term! Think volume!