20 - 30 minutos
Trying to fix bad WiFi reception. Battery change did not help. It was a good thing I did change the battery however, because it puffed up like a balloon when the motherboard was unscrewed.
Very uneventful. I followed the ifixit photographs and steps without a hitch.
If the phone is more than 3 years old, replace the battery. A magnetic parts tray is very handy to keep everything together.