My iPhone screen turns black aftert approx 6-7 hrs of charging and won't turn on
My problem goes like this
About two weeks ago I tried updating my iPhone 5s to iOS 8.3 using wi-fi
A problem occurred while updating and I had to connect the phone to my PC
I had troubles downloading the update and installing it on my phone, but after 5-6 tries it worked
The general problem is that now each time I try to charge my iPhone with a wall charger, after 6-7 hrs or a night of it being plugged in I wake up to my iPhone having a black screen and not working
If I connect it to a PC, it will say that updating is not possible, only restoring
Then I restore it and after using it for a whole day I try to charge it again
And in the morning the same black screen thing happens
I went through this cycle about 10 times by now
My iPhone has been checked in an authorized service and they told me the hardware was fine enough
What can possibly cause such a thing? An improperly working socket?
A broken wall charger? Some kind of an electricity jump (which is ridiculous, why would it happen every night)?
This all started with updating to iOS 8.3, my iPhone was working perfectly before
iPhone 5s, iOS 8.3, Purchased 14 months ago