Developer Options -> Install Via Usb Still 'refuses' To Get Switched-on

[zzpzaf]

After following this 'untold' whole process of unlocking my brand new Redmi Note 5A MDG6, I still have this issue. My device is now unlocked, however I can't switch-on the 'Install via USB' option. I've tried almost any googled suggestion, but no success. I bought this phone especially for my development needs (Android Studio), and it remains unusable. It's a pity spending so much unproductive time... Please, help...

NO Problem any More ! Solved!

 

[ingbrzy]

you have to sign in to your Mi account..

 

[zzpzaf]

you have to sign in to your Mi account..

I think that this is obvious that I am signed in...