I would never pass up the interview, if for nothing else practice and experience. If they offer you something, you have that decision to make. Honestly I would be surprised if they hired you given how recent they were, but I am honestly surprised they invited you for the same reasons. I would say show up, put your best face forward and give it a go. Explain what you did wrong and why you failed, but be ready to also explain what you learned and how you are going to apply that to your future career.
Best of luck, show up for sure.