1) Awesome Font icons are not displaying properly (just squares) when SSL activated.
2) If there is any other mixed content (images or api / font calls) this needs to be fixed to.
3) Front end shop should be fully SSL compliant with green padlock in browser with no errors.
4) Correct rewrite rules and redirect in htaccess to ensure no loss of page rank or indexing.
5) All files that have been changed must be noted in final protocol for our records.
This is a common problem for Opencart 2.0 and simple to fix once the troublesome files have been identified.