Replaced battery because of significant bulge causing erratic track pad behaviour and must say this guide was perfect.

just completed this very easy battery replacement on my daughters iPhone 4s. Steps are really easy to follow, one thing I found helpful was to use a tweezers to put the pressure contact back underneath the top screw of the battery connector!

my local apple authorised repairer quoted me €80 to replace the battery in an old iPhone 3g that my daughter was using, after some searching i came across this site and decided to take a chance on the replacement kit!

once it arrived it took me approx 15 minutes to replace the old battery, some of the ribbon connectors were fiddly to reconnect but overall an easy- moderately difficult job!

great step by step help tho! thanks a lot