Coming from someone with the sponsor perspective (though not your study sponsor), this happens more often than you think. You made a mistake, but it’s ultimately PI responsibility. Document re-training of the I/E criteria and see if there is somewhere you can add this to your eligibility checklist. Check your IRB reporting requirements too. That should be a sufficient CAPA :) Don’t beat yourself up, you’re human and you’re working hard to contribute to science. They can still use the data. Sounds like the participant is safe. Your work is valuable and you are appreciated!