10 - 30 minuten
My GF had issues with her iPhone4s' battery, at start, the device was shutting down by itself while displaying 20% battery left. It got worse and worse, starting to shut down arround 30%, then 40%, then 50% (she really started raging at that point)... Knowing the price of an iPhone6 and the fact that despite the battery, she was still happy with the phone, i decided to try to fix it.
Repair went pretty well, i didn't know what kind of screw were used on GF's iPhone so i bought the batttery pack with the freedom pack (special screwdriver with it) and it was welcome as there was two specific botlob screw that, even with the proper tool, were quite hairy to remove and didn't go without struggling. Once the weird screws removed (thanks for the regular replacement screws provided in order to get rid of the botlob ones), battery replacement went like a charm.
Quite easy to replace, i really recommand to get the liberation/freedom pack if there are botlob screws. Once special screws step passed, replacement is really easy