20 - 30 minutos
My iPhone kept saying the battery need charging when I had just finishing charging it. I would be talking on the phone when it would shut off because of the battery.
It went very smoothly to my surprise! The hardest part was opening up the top casing, but after that it was easy. The instructions were great and my phone is working fine now!
Make sure you do the step by step process and you shouldn't have any problems,