So I recently found out that my 360 controller is very rusty on the back and especially on the battery board and it just...

There's something wrong with your battery, try sending the phone to a repair shop and ask the worker to remove the back and check for any damages. Or maybe it's a virus, some viruses overheat your phone.

Check if there's any dirt in the microphone, clean if there is any. If that doesn't work then maybe there's something really wrong with your microphone or your cell phone itself.