I am trying to turn off the backlight on the soft keys (home, menu, back and search).
My phone is a HTC Evo 3D running Ice Cream Sandwich. Before, I had Gingerbread installed and I could use "Screen Filter" app to turn the lights off. After the upgrade, "Screen Filter" no longer works.
On one forum it says that if you edit the file
max_brightness in folder
0 and then switch the screen off and on again then the key lights stay off.
However, the file is read-only.
I want to make the file writable. Do I need to root my phone to do this?