20 - 30 minuten
My iPhone would turn off at random times, especially if the battery showed less than 80% charge.
The repair process was pretty simple. It was somewhat difficult to remove the 1st connector from the display to the logic board. I couldn't see the connector well enough to determine where the connector and logic board met. I didn't want to just pop it off b/c I was afraid I would destroy something so I took it easy and finally got it disconnected. After the 1st one was off it was easy going forward. Replaced the battery and re-assembled the iPhone without incident. Turned it on and its back to working like brand new. Good thing too b/c it doesn't look like Apple is in any hurry to release a new iPhone. :-(
Take your time.