Hii Nikhil..

I think you should apply for counselling process under UPTU examination for admissions at engineering colleges as you have performed quite well. 

And if you are having compartments in your class 12th boards examination then you can either reappear in the exam in the compartment exams and clear it then their will be no issue for taking admissions at engineering college.

Other than this you have a option of NIOS exam where you can reappear in the subjects you have failed and get passing marks in boards without wasting a year. It is acceptable throughout and will have no issues. 

Hope it helps. 

Best of luck for your future. 

You need to clear your paper only then you'll be able to get a seat in engineering through upsee. Rank doesn't hold value if boards not done completely. You need to first attempt to clear all that only then your admission would be legible. Rank in upsee does not hold any seat unless you get a letter of completion and marksheets with passing criteria to be elligible enough in the counselling.