Coursepress 2.0 update - HTTP 500 Error

Since updating to coursepress 2.0 my site has broken.

- When a user tries to sign up using woocommerce and stripe, I get the error 'Internal Server Error' within the checkout page.
- When I try to preview the unit pages I get HTTP 500 errors
- Some stand alone pages that we're working fine before now get a 'too many redirects' error.

These are the problems I have found so far.

Things I have tried so far...
- updated all plugins
- deactivated all plugins try look for conflicts
- used the default coursepress theme

Plus followed and completed these support suggestions -