I wanted to activate my husband's old iPhone, but it needed a new battery.
The battery arrived earlier than expected, which was a nice surprise. Using ifixit's guide and powerful reading glasses, my husband and I were able to replace the battery easily and successfully! The photos and instructions made it easy. So, for less than $20.00, I now have an iPhone, and, according to my 13yr old, I finally don't embarrass him when making phone calls in front of his friends. Thank you, ifixit, for restoring my social status among 13 yr olds!
Don't forget your glasses! Those screws are TINY. As we removed the screws, we corralled them inside a clean, dry water bottle cap so none would escape during the operation. It worked for us!