AES file decryption failed due to wrong password

Hi there
Recently My brother forgot his aes lock usb at home and he told me to send it by email after decrypting it but due to my carelessness,it says ,device is locked -refer to administrator.Is there any chance to recover those files by him when he come back?As I heard that they cannot be recovered again.Is that true?
Regards mila

Sorry, what does this have to do with the My Book Life NAS?