Share your experience!
So you have repaired via sony update service?
http://www.sonymobile.com/gb/tools/update-service/
I have tried it but still no change
My phone resets occasionally when charging. It reaches 100% then resets itself and either continues charging or restarts charging from zero.
Never happend with Android 4.1.2.
I know the some thing happens. I used to put my phone overnight to charge now I put it in the morning.
Do you have a trimmed micro SIM?or you bought it like that?
I put my phone on charger before I go to sleep so I can turn it off manually when the charging process is done. I used to leave it on charger all night while phone was using Android 4.1.2, but now I must wait till it reaches 100%. Unbelievable.
I use SIM card issued by my mobile operator. I worked well on Android 4.1.2.
Same happens to me too. 3rd time this morning. 
This needs to be fixed!
Two new things:
1. I left Xperia SP on charger all night last night (because I fell asleep), and in the morning the LED light was red as if the battery was still under 90% and charging. When I checked the battery capacity level, it indicated that the battery was 100% full.
2. In case when Xperia SP is switched on, and I plug in the usb cable for charging and continue to use the phone either to check the battery capacity level or to do something else, the screen won't switch off by itself. I have to switch it off manually or it would remain switched on forever.
My friends laugh when I tell them about horrors of using Xperia SP. It is unbelievable that such a big company like Sony with such a long tradition does nothing to improve the situation with Xperia SP.
try to boot in safe mode and let your phone charged..see if it will switch off or no
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008