Hello Pratiksha,
No, Board marks not consider in JEE exam or during admission in NITs but you must follow the eligibility criteria to take admission in NITs like your % in 12th must be more than 65% for SC.
Here is the eligibility criteria for NITs
Foradmissions toNITs/ IIITs/ GFTIs:

• Candidates need to have secured a minimum 75% marks in class XII or equivalent exam or be in the top 20 percentile in their class XII exam conducted by the respective board.
• For SC/ ST candidates, the eligibility criteria are to secure 65% marks in class XII or equivalent exam.

Visit to the link for more details
https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-eligibility-criteria/amp
Hope this would be helpful.
Good Luck!