I have taken on many interns over the years both when I was an in-house executive as well as for my consulting firm. Some have been excellent. Some have taken a lot of effort to manage. Are you able to gain an introduction to someone at the startup from someone who knows the quality of your work? That would be optimal. Other suggestions are showing that you will be very diligent, reliable, and fast learner. That you deliver and are eager for the opportunity. Internships are tough because they often take more effort for the manager to manage than the value they gain. Providing assurance through references and work results will help the potential opportunity see the value you can bring to them. I'm happy to take a call from you for follow up questions.

Very best,
Grace