I thank you for this very important help indeed, I am a new technician and unfortunately I am gaining experience at my own expense and I am fine with that. I will definitely start studying these schemes, to understand how they work, I hope in the future to do some welding so as to put these experiences in my pockets as well which completes the type of work that I have chosen very happily. Surely in the not too distant future I will cover the voltmeter and I hope to be able to get a soldering iron too. I can tell you that at the beginning they were only the standard Xiaomi ringtones, while on channels like YouTube it was fine. As soon as I put the phone on charge, the music on YouTube also stopped and from there I began to doubt whether the problem was in the motherboard and therefore writing for the first time on this site