Maa Changes the Meaning, Not the Form

Negative Past Tense (Maadhi Manfi) - Active and Passive

The negative particle مَا is non-governing here.
That means it does not change the letters or vowel marks of the past-tense form after it.

NegativePositive
مَا فَعَلَفَعَلَ
مَا فَعَلْتَفَعَلْتَ
مَا فَعَلْنَافَعَلْنَا

Only the meaning changes from positive to negative.