How to permanently disable mobile data on a rooted Android device?
I would use your phone's test page to disable it... It's like disabling an adapter on a computer are its devices software it will still look like it's on but you can change your way you speak to your tower from like 5 seconds 10 seconds 30 seconds and disabled or immediate. I use phone dialer to pull up the test page *#*#4636#*#*