10 - 15 minutes
I had severe problem with the ear speaker and it started to develope battery discharge issues. I live in a remote area where servicing will take 2-3 weeks. And I have a terrible fixation with understanding everything I use.
The repair when swimmingly, until I got a little over zealous with cleaning the guts out with a cotten swab and isopropyl alcohol. I broke off a (what I assume to be a shield contact arm for the ear speaker) thing, and soldered it back together. I cleaned both parts with aforementioned alcohol and put just a titch liquid RMA flux on both. Then while the flux dried I set my iron to 200c. I then applied just a scosch of solder to both sides of the joint and joined them. Clean again (more carefully) test the joint are voila!
Read the above. Be patient, thorough, and patient. And don't forget Occam's Razor.
iPhone 5 Replacement Battery
iPhone 5 Earpiece Speaker
iPhone 5 Liberation Kit
Probe and Pick Set