@Admin BERRYWORKS VENTURES I am glad that post upgrading your subscription the webapp is able to start.
Here are some of the action plan which you can try to follow to isolate the below issue:
Plan 1: If the bot doesn't work in Test web chat, then follow the steps mentioned here.
Plan 2:
You can also test and debug with Bot Emulator.
Plan 3:
The forbidden error you are encountering is related to Authentication. Ensure that you follow the steps mentioned here.
Plan 4:
While testing in webchat or using directline, Collect HAR traces to identify the cause of this issue.
Plan 5: Please enable the App Insights and check for the cause of Forbidden error.**
Hope this helps.