Codeigniter Website Showing Blank Page in AWS Elastic Beanstalk

Unless you are moving it to an environment 100% like the one you tested, things like this happen. A blank page can mean several things such as Apache works, but it isn't being routed correctly or there is a PHP error and the php.ini is set to not show errors. Time to troubleshoot by looking at the access/error logs for Apache.

I'm assuming you set the DirectoryIndex appropriately?