Chosen Solution
This Iphone 7 plus was “repaired” at a local shop, the battery and screen were replaced but ever since everytime she tries to use the phone she cannot hear anyone, they cannot hear her and speakerphone option is grayed out. I replaced the speaker after finding the other one was damaged but still no change. I also discovered several missing screws and a knick across one of the ribbons, From the looks of it it wouldnt be surprising to find the front facing camera ribbon has gotten damaged but this seems like a different issue to me.
the 1 pic is just showing the missing screws, this was the 1st thing i noticed when I opened the phone.
2nd pic is showing what Id guess is a screwdriver knick from slipping off one of the screws
and the last pic is just showing the damaged speaker I replaced.
It seems like related to Audio IC issue which is a very common problem with iPhone 7 and 7P. Some broken connection under the Audio IC is responsible for this issue. Audio IC has a pad c12 which is connected to a near by resistor R1103, you need to repair that broken path by putting a jumper wire between C12 & R1103. This is the right solution for this problem. Some time in rare case may need to repair J12 and H12 pads also.
