Hi, I'm using Z1 C6903, now the home and recent apps button on my phone is not working, I pressed but nothing happen, same with the lockscreen, even I set to PIN lock, after I unlock the screen, there is no PIN lockscreen, so my phone cannot be locked. I clear dalvik cache and wipe cache partition in recovery, but the problem did not disappear. How to fix this? Even in safe mode the button is not working too.
I'm using kitkat 4.4.2 14.3.A.0.757