What does the ma'mum do if the electricity goes out and he does not hear the imam's takbir?

The questioner : Some mosques consist of two floors... The congregation prayer is on one floor... The second floor or the reverse, with the imam on the upper floor, and the loudspeakers are what convey the imam's actions to those below. Sometimes the electricity cuts out during the prayer, so what do the worshippers who do not hear the imam's takbir do?

The Shaykh : He intends to separate, he intends to break away.

The questioner : And they pray individually?? Or does one of them step forward... No, one does not step forward, teacher?

The Shaykh : No, one does not step forward; they become two congregations.