The ruling on those who lose the imam's voice during the Friday prayer

Question:
A group prayed the Friday congregational prayer on the second floor of one of the mosques, and during the prayer the amplifier stopped working, so they could not hear the imam's voice. One of them stepped forward and completed the prayer for them?

Answer:
There is no harm in that. Fine, they complete the prayer with him, and praise be to Allah.
Q: Do they complete the Friday prayer with him?
A: Yes, they complete it with him. Did they pray one rak'ah, or did they not pray a rak'ah?
Q: He says: during the prayer.
A: If they prayed one rak'ah, they complete it, like the one who catches one rak'ah of the Friday prayer.
Q: And if it was less than one rak'ah?
A: Yes?
Q: If it was in the first rak'ah?
A: It appears that if it was in the first rak'ah, they pray Zuhr, they do not pray Jumu'ah. They missed the Friday prayer. But if they caught one rak'ah, they complete the Friday prayer.
Q: And if they heard the two sermons, do they pray it as Zuhr?
A: Yes?
Q: I say: they complete Zuhr even if they heard the two sermons?
A: Yes, but they did not pray with the imam. They missed the imam's prayer. They did not pray with the imam.