Wtf happened?

So i tried today to make my kqi3 pro go from an eu to us version to get 32kmh .followed the steps,installed the other niu app,copy pasted the link etc lifted my rear wheel and 32kmh was there.now i left it and After a few hours i actually had to go out and when i used my scoot my brakes weren't working? Or at least very very badly,freaked out,deleted the unofficial niu app(also it would disconnect me and whenever try to load it tell my a new update is available on the unofficial app) and installed the normal one instead,tried it again and now my brakes were just fine AND i still had 32km/h(it seems like it went from an eu to us model directly on the real app idk how but without the brakes problem)

Another issue aswell but this ones been here for a couple weeks: is it normal for my wheels to drift when i stop the vehicule? Whenever i'm going past let's say 18kmh and brake i can feel the scoot kind of drifting and hearing a noise as if my wheels were scratching against the pavement(same sound as when someone drifts kinda) i asked a local cyclist and said it's normal.is it tho?