15 minuten - 1 uur
6 hours into the day I'd have 40% battery left and then the phone would shut off. Plug it in and it would show 40% ... I was ready to throw the phone out the window. Clearly the phone was confused about the battery capacity and it looked like the battery capacity was actually degraded (and not that I had a problem with apps sucking down my battery)
Was pretty easy to do -- though the first time I reassembled it I noticed the top-right corner of my screen would get really hot. The battery life was better but not as good as I'd hoped. A few days later I took it apart again, re-seated the 3 connectors for the screen, and the hotspot is gone. And now, 13 hours later, I still have 70% battery!
Read the instructional text in addition to the video -- there are details in there that aren't in the video which I wish I'd seen before.
I also used a heavy object to lean the screen against to hold it at a 90 degree angle while it was still connected to the main logic board so I could work on the screws and whatnot with both hands.