There are two problems
1) Invalid or no certificate authority found from PayPal
2) There is no redirection from my e-commerce site to PayPal
3) There is no status response from Paypal to my e-commerce site
This is a simple implementation, 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!
Attached is the PayPal log file. I have written all the necessary codes, just the above problems require your solution.