5 - 30 minutos
After two years of use the home button was only registering a click 50% of the time, and the battery didn't quite last as long as it used to.
Replacing the battery was very quick and easy. Replacing the home button was quite difficult but very rewarding once the phone was put back together!
Highly recommend replacing the battery, quick and easy. I would recommend replacing the home button only if you are very patient and careful with all the delicate connectors. This was my first time taking an iPhone apart so thoroughly and there are several tricks that are mentioned in the guide as being important, pay attention to these notes. Also give yourself plenty of time to complete the 30 or so steps to get to the home button.
Magnetic Project Mat
Pro Tech Toolkit
iPhone 4 Replacement Battery
iPhone 4 Home Button Assembly