Hi! The certificate installation, if you are sure that it was smooth and successful, then updating the links in the OpenCart store should not be a problem. I might also need to add a quick couple of lines to the apache config file, if needed (generally not required). I hope that you have access to the apache config file, should there be need. But, if the installation of the certificate is not proper, then the certificate has to be reinstalled and the application reconfigured for using SSL. Look forward for helping you in fixing the issue.
- Best
Avinash T