What should I do to pass in the JEE Main in 20 days?

You need to utilize the time you have left efficiently. Rather than covering new subjects, it will be better to revise the topics you have already covered. Also, start solving past year papers, to get an accurate idea about the examination pattern and the topics that have more weightage. Solving different series and mock tests would have been effective if you had more time. Since you have less than one month solving past years’ papers for JEE Main and AIEEE will be better. It will give you a confidence boost.