Cannot charge battery via usb cable to pc after upgrade firmware and android version to 4.1.2 (Galaxy S2)
Many USB ports on computers do not have power sufficient to charge a phone battery.  Does the phone charge with the plug-in type supplied with it? Some computers will advertise a charging USB port.  The default current (amps) is 1/2 A or 500mA in a standard USB connector.  It is not uncommon for tablets to require 2 Amps.