F1 Visa First showed approved and then Refused

My son under the drop box case dropped his papers at VFS Delhi for his F1 visa. He has already studied in Usa and retuned without any infringements ever. Within a couple of days the status of Visa showed “Approved”, However today the status is “Refused” with a long note. No other communication has been received from the Embassy ! What does this mean ? Why was it Approved before and now Refused. Can some pls elaborate and clarify. Thanks

What is the note about?