Being unable to hear the Imam for a portion of the prayer

Question:

A group of people offered the Jumu'ah (Friday) prayer in the basement of the Masjid (on the ground floor, i.e., the Musalla was upstairs) and during the prayer the electrical current was cut off. Then, those who were being led were unable to hear the Imam, so one of those being led stepped forward and led them in the rest of the prayer. What is the ruling of these people's prayer, since he led them in the rest of the prayer performing it as the Jumu'ah prayer? Also, what is the ruling if no one steps forward? Does each of them complete his prayer by himself? If that is permissible, then does he complete the rest of the prayer as Zuhr prayer or Jumu'ah prayer, since he listened to the speaker (Khatib), started the prayer with the Imam and prayed one Rak'ah with him?

Answer:

If what the questioner mentioned has occurred, then the prayer of all of those people is correct, because whoever caught a Rak'ah of the Jumu'ah prayer, then he caught the Jumu'ah prayer, as is reported in an authentic Hadith from the Messenger of Allah. If no one had stepped forward and each of them prayed the last Rak'ah by himself, then that would have been sufficient for him. This is like the person who misses a Rak'ah and he prays whatever he catches with the Imam, then he makes up the second Rak'ah for himself. This is according to the generality of the prophet's statement:
"Whoever caught a Rak'ah of the prayer, then verily he caught the prayer." (Al-Bukhari no. 580 and Muslim no. 607)
and Allah is the Giver of success.

Source :
Shaykh `Abdul-`Azeez Bin Baz
Fatawa Islamiyah vol.3 p.24-25 DARUSSALAM