Wipe cache partition is done in Recovery Mode. Turn off device. Press and hold Volume up key, Home key and power button at the same time. When the phone vibrates, release the Power button and continue to hold home and Volume up until Recovery screen appears. Release keys and using the Volume down key move to Wipe Cache Partition then use Power button to carry out wipe. Reboot will show and Power button will enable. See if that has the desired effect. Neil.