No need to format bros,
Solution Is Just,

Dial- *3646633 in the home screen, u will see engineer mode select 5th option 'Misc' then 6th option 'Assert Testing' now your phone will restart, now u can able to enter menu go to settings & select 'Dualsim open' mode.

For S4 Flight mode,

Use Stick click Home Key In The Icons In The Left (only on touch screen)
Ur Menu Will Be Opened go to settings Just Change From Flight Mode To Dual Sim Open.
_________________