W580i back key not working

Hi there,

I am a noob to this forum. For some reason back key of my SE W580i is not working. I tried dissembling the phone, removing flex cable and fixing it again but it still not working.:a003
Does anyone know how to assign some different key in front panel as back key through software as all other keys working fine.

Thanks

change flex and post result.

replace flexible .. if you still have problems check keypad ic ... post the result