Microphone not functioning after replacement.

So this year I've come across an iPhone 7 Plus that has the iOS 13.5.1 and the client says that the microphone has stopped working around November-December of 2019. I replaced the iPhone 7 Plus Charging Dock Flex Cable and the phone still behaves the same. The Bluetooth headsets/speakers that I connect it to will allow the phone to record and hear sound fine but only through the phone or voice memo app. The voice memo app won't even attempt to record sound without a BT connected. I've tried connecting a lightning headset to the phone and still nothing. The video or ANY app that uses video will Not record any sound however , Bluetooth or not. The speaker that is connected to the Charging Dock Flex Cable has ALWAYS worked, the charging has always worked and so after replacing the flex cable this leads me to believe that this was a software/firmware issue. I am considering jailbreaking to revert to an older iOS (maybe before November 2019) but before I do, I would like to exhaust all options. I have never jailbroken a phone before and am trying to be cautious. What are your thoughts on this issue if you please? 

It should be noted that the phone went back to behaving with the same dysfunction after the part was swapped.