The Qaqet sounds b, d and g (the voiced plosives) are always preceded by a short m or n (a nasal sound): mb, nd and ng. If this nasal sound is missing, a Qaqet speaker hears it as p, t or k (the voiceless plosives).
And this is the source of the misunderstanding: the child says batri(k) ‘battery’ (without the nasal), and the mother pretends to hear patri(k) ‘Patrick’. She then attempts to teach the child the proper pronunciation, exaggerating the nasal sound and saying very clearly mbatri ‘battery’.