Chosen Solution
When charging my I-phone 7 it has an intermittent beep which is really annoying which I cannot stop even by muting the phone. How do I switch it off?
Have you tried another charger by chance? It sounds like you may be having some type of whine from a component that might be giving out. I dont much about logic board repair and component level issues, but I bet the charge IC or some other component is become stressed when charging. If you are comfortable with opening your phone and it’s not under warranty, I’d order a new battery and test it before full installing just to rule it out.
