I had this problem, I to thought i had somehow bricked the phone I took the back glass off again and found that I had put some of the screws in the wrong places.
it probably caused the phone main board to not earth correctly, therefore preventing the charge circuit from working correctly.
- take back glass back off (annoying but necessary)
- take all screws back out of black plastic shroud. (if screws are in the wrong holes like mine were this can be difficult)
-put two smaller diameter but longer length silver screws either side. of battery.
-put 3 shorter fatter golden screws above and below the battery. (1 above 2 below)
- tighten screws.
- plug in to charge wait 10 minutes to make sure it is now charging. (mine took this long to start working again. as it still turned on and off a couple of times until it got to 2 %. then it charged normally)
- replace rear glass once you are happy it is now charging.
Hope this helps.