power button was unresponsive

I have the same issue. I replaced a broken screen for an ipod 4 and the customer returned after a couple of days complaining that the power button was unresponsive at times and the volume up button would turn off the ipod.

I inspected it and sure enough the volume up turned on/off the screen. I disassembled it and put it back together.

Major problem now, nothing connected to the flex cable works. I am thinking about replacing the flex cable, but fear messing it up completely. I will try it and get back to report.

If anybody has an idea what it could be, please comment. I need as much help as possible.