New Low Microphone Volume While In Calls (note3pro)

[artearte]

Hello everyone, my father's phone (Note 3 Pro) had worked perfectly for close to a year with stable 8.0.1.0 but a couple of weeks ago his microphone volume died almost completely.

You can hear pretty much nothing unless you blow on the lower microphone or shout really loudly, he has to use speaker mode all the time in which it works fine.

I tried upgrading to the current stable 8.1.something but it doesn't change a thing so I rolled back to the previous one through a backup. I have lots of experience with unix systems but not with android, please help?

 

[artearte]

Also posting what I tried already apart from new ROM with dalvik/cache wipe

About 10 different build.prop versions from posts around this forum and google (had to chmod 775 it or the device would bootloop, I think the file manager I had used messed up with perms)

Portrait video trick thingy

Google Now settings, the app is not on the phone nor has it ever been.

If anyone has any ideas then please help, the bottom microphone audio is awfully low in all occasions, even with the QC tests, the device is pretty much useless right now.