I have this battery problem with my iphone 6(10.0) for over a month now. At 100% battery, it drains very quickly and most of the time the battery percentage jumps from 60% to 30% etc. And from 20% when the warning shows it then jumps to 1%.
I already tried draining iphone and fully charging it then reset the phone. I want to update the os but I need 10.0 in my work. Does my iphone battery have any chance working again properly?