Chosen Solution
Hello IFixit, I bought a new LCD frame assembly for my Samsung Galaxy S4 I9505. Screen works fine, but the left + right button on the bottem of the screen are not lit up and not working. I tried my old flex cable for the buttons. They work and lit up aswell. My thoughts now: 1. Faulty softkeys flex cable 2. Flex cable is not working on the current version of the phone. My old flex cable is a : DS.HF.R 0.9 D46K is working with the phone. But on my new LCD assembly is a flex cable for the softkeys: DS.HF.R 0.9 D35C. Going to try a few roms today.
It’s a faulty screen. The soft keys connect via a cable from the LCD preassembled frame to the charging port ribbon assembly. Get another screen and you are good. I always test that before installing completely. You can’t just replace that part since it sits under the glass. Attempting to do so may result in a cracked LCD with no display. It’s never software issue if it doesn’t work on the new screen and works on the old one.
What did you find out? I am currently experiencing the same issue after screen replacement on an i545 S4 Verizon.
