After installing “ExtraButton v1.0.1” on my Nokia 700 (Belle), i couldn’t adjust the display brightness from the Settings menu.
Tried to recover it just by uninstalling the app: DIDN’T WORK.
Re-installing the firmware with Nokia Suite : DIDN’T WORK.
Alhamdulillah, by restoring the device to the factory settings : WORKED successfully.
*) choose Restore to the Factory settings WITHOUT DELETING DATA.