Pre-Assessment with only one attempt

I have a welcome page which has two buttons, Pre-Assessment and Course. upon clicking Pre-Assessment button, the learner is directed to Scene 2 Pre-Assessment slide 2.1 upon clicking Course, the learner is redirected to Scene 3 Main Course slide 3.1. Now when the learner leaves the pre-assessment midway, or refreshes the browser midway in the pre-assessment, i want the learner to land up on the course, ie 3.1 and not be given the option on the welcome page. That is, only one option to choose between the pre-assessment and the Course on the welcome page. How do I achieve this?