10 - 30 minuten
I got a friend's iPhone 4s that hadn't been used in a while, and the battery was shot.
The repair went fine, ALTHOUGH there is a TINY PIECE that becomes dislodged once you remove the screws that hold down the battery connector. I didn't notice the paragraph about it in time in the iFixit manual. Luckily, in the video I watched, the same thing happened to him, and he details how to put it back where it belongs. Here's the video I used https://youtu.be/RW8RSA51VlY
Just keep your eye out for that tiny grounding piece that comes loose when you remove the battery connector screws! This is noted in the iFixit manual, but it doesn't grab your attention the way it should (or at least it didn't grab MINE). So make sure you don't miss this golden nugget of advice...
Take notice of the position of the small black ground clip on the upper screw of the battery connector. This clip is attached only by the upper screw. When reinstalling, it must be aligned so the gold contact point will press against the back cover.