One advice is that my friend should summarize the experience. He should carefully analyze why he failed this interview; he is supposed to consider whether his performance is good enough, whether his background is suable enough for his job. After analyzing these factors, he will perform better in the following interviews.
The other advice is I will advise my friend to find a job in a different field. Maybe his ability and skills are not competent for this job, but his ability and skills might be qualified for certain jobs in other fields. To try to find a job well matching his condition and skills, he will be more likely to succeed.