SP virtually unusable after update

[AndreasTag]

I recently installed the latest android uodate on my Sony Xperia SP and in the following days the phone became essentially unusable, with no programs working and the phone has begun randomly turning itself off and on again. I have tried to perform a  factory reset however when I eventually reach the screen with the 'Erase Everything' button on it, once the the button is pressed it does nothing.

This is not the first time I have had this problem however last time the same update was installed I eventually managed to perform a factory reset but it seems virtually impossible now. Can anyone help?

[Frustrato]

A very similar problem appears to have occurred on my SP. I have sent in my phone to Sony for a repair under warranty as it is not possible for me to determine the cause of the fault and this appears to be the only route for it to be addressed. I await the response from Sony with avid interest.

[LukaLuxXD]

Do a software repair via PC Companion

[AndreasTag]

I've tried this, when I try and connect the phone to my PC an error message appears.