technically the penalty should have been $205 (the penalty for filing 1 month or fraction thereof late for 1 partner) x 2 (number of partners) X 4 (number of whole and fractional months late) = $1640. the fact there were no profits is irrelevant.
3/15/19 to 4/15/19 is one month late. file on 4/16/19 and you now are 2 months late (1 month and a fraction)
writing a letter and asking the penalty be abated usually works if this is the first time the return was filed late.
hopefully, you filed the 2020 return timely.
