20 - 30 minuten
I inherited my wife's iPhone once she upgraded to a Samsung Galaxy. Her old phone would only function for longer than a minute or two if it was plugged into a power source.
A replacement battery was just what the doctor ordered. The step-by-step instructions made the operation simple. My only snag was right off the bat pulling too hard, too fast on the suction cup to remove the display. This yanked out the first three ribbons altogether, but luckily did no permanent damage to them. The only shortfall is that the camera lens now does not function. I can still take a screenshot so I think I will re-open the phone sometime and check it.
Slow and steady will win this race. Look over the pictures a few times to get familiar with the steps and follow them exactly. Lay out a hand towel on your workbench to catch any "lively" screws you encounter. The old battery will be stuck hard to the case so use a hairdryer to warm-up/soften the glue and steady pressure with the spudger will do the rest. Keep in mind that the new battery will not have the natural sway to it that the old battery has developed over time, so cramming everything back together will be a tighter fit. But you can do it. Good luck!