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I'm not sure what you mean, could you please elaborate? Have you tried to perform a software repair in PC Companion but still experience the same behaviour? If not, you can perform the repair by following these steps:
In PC Companion you press start on Support Zone > Start on Update the phone/tablet software > Repair phone/tablet (the blue clickable link in the message) > Follow these steps without having your device connected to the PC.
Follow the instruction that appears in the program and do not connect your device until this guide tells you how to connect it.
But if there are no improvement, it sounds more related to a hardware issue that needs to be examined and fixed by a technician at an authorized service center. I suggest that you contact your local support team for further information about how to proceed with this in the best possible way:
http://www.sonymobile.com/global-en/support/contact-us/contact-info/
