Ask HN: Should I relearn everything that I have learned?

I recently interviewed with 3 good startups in India(HackerRank, HackerEarth and Wingify) for summer internship and got rejected from all of them. While I was able to answer the some questions with ease I wasn't able to answer the questions which weren't so straight forward. Like during my wingify interview the interviewer asked me if I had to implement to two way binding, how would I go about it? I wasn't able to answer as I hadn't used angularjs much(he picked it up from one of my github projects). Also, when he asked me about REST principles I couldn't answer it well enough.

Now, I am considering two options. Either I join a programming bootcamp (there is a very good one here in New Delhi) and relearn everything or I opt for a mediocre startup and learn things as I work. Since this is going to be my last summer before I graduate, I want to use it wisely.

Looking for some advice.