do board marks matter during placement at lawfirms
Nope! Board marks don't influence a lot during placement. But see if you suppose a situation where you and another person are equally good and the officers who came to select can select one then they might consider your entrance rank as a parameter to tie break. But apart from that there are lesser possibility of considering the board marks for any of the incidents during law placements.
I hope this answer helps. All the very best for your future endeavors!