It is said that Yogmaya flew off to Heavens freeing herself from the clutches of Kansa while announcing to Kansa that your killer has been born. Scriptures do not clearly mention that she too got killed like other siblings of Krishna. However more knowledgeable are requested to throw light on it.
Yogmaya was also an incarnation of Shakti who came to be born along with the incarnation of Lord Vishnu to keep some old promise. When Kansa caught her by her feet and hurled her to the ground, she flew towards the heave, saying “Kansa, your killer has already taken birth. I could have also killed you but since you caught me by my feet, I take it as your expression of humility and am pardoning you”.
Krishna was born in the darkness of the night, into the locked confines of a jail.
However, at the moment of his birth, all the guards fell asleep, the chains were broken and the barred doors gently opened.
Similarly, as soon as Krishna (Chetna, Awareness ) takes birth in our hearts, all darkness (Negativity ) fades.
All chains ( Ego, I, Me, Myself ) are broken.
And all prison doors we keep ourselves in ( Caste, Religion, Profession, Relations, etc ) are opened.
And that is the real Message And Essence of Janmashtmi.
Happy Krishna Janmashtami