Hello Aspirant.

As you've mentioned that you've scored 40 percentile in JEE main examination but got 300 marks in Tamil Nadu board in 12th. This means you've got nearly 60% aggregate in 12th which doesn't satisfies the eligibility criteria for you get any NITs or GFTIs or colleges through JEE main examination as for PWd category candidate it's mandatory to score atleast 65% in class 12th examination.

You can get admission in any private university or college at this percentile but won't get any Government universities.

Best of luck