Battery replacement. Old battery would not hold a charge
With the help of iFixit, the repair went flawlessly. Right parts with the right help guides made the repair very easy.
Be cautious removing the 'Liberator' screws from their packaging. They are very very small and easily dropped! (Speaking from experience) and even harder to locate once dropped... sigh...
With the help of iFixit, anyone can fix the basics of an iPhone, even if you're not terribly mechanical