Contact Form 7 Validation

Hi, I am using contact for 7 with divi theme. I would like to perform data validation on one field (serial number) after data is entered into that field but before other fields are completed. The form natively does this for required fields but I would also like to check format of the field data and also if that value already exists on the database. Could you tell me what would be the best hook to use for this. I can get the wpcf7_before-send-email filter to work but it seems to fire after the submit button is pressed. I cannot get wpcf7_validate_text to fire. Thank you

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