Started happening to me too!
Get a flashing battery icon continuously too.
In no connect USB cable, it show the battery icon like cable already connected! (lightning pic in the battery)
When I search in Google, I got forum.xda-developers.com
I understand the idea of problem, of my Hardware fault finding experience
I clean the USB port in (The Samsung galaxy 2) PDA phone
gently and I am connecting to charge or computer cable,
Straight,slow, careful, every time
Last 7 days no error popup coming !!!!
Thanks to all
What is the manufacturer Answer