Jamaat Salaah and Imaamat

Sound system malfunctioning during the fardh salaah

Q: Some people were reading salah in the main hall and others outside the hall. The microphone got cut half way through, such that the people outside the hall couldn't hear the imaam or see him. There was also no one to call out the takbeer. What is the ruling in this case? 

1. Is the salaah valid for those outside despite the mic being off throughout the rest of the salaah? 

2. Some people broke their salaah and some carried on. Is their salaah valid? 

3. If the mic was to start working again, then can the people outside carry on and catch up to the imaam?

Father correcting the son for missing salaah in the musjid

Q: On one occasion I missed Salah in the masjid. In this case I read it at home. I understand this is not ideal however if my father comes to find out about this he claims that I have a shaytaan in me. This is understandably upsetting to me. 

1. Is it okay from a Islamic perspective for him to say this to me? 

2. If so, what purpose does it serve?