20 - 30 Minuten
Needed to change the battery because phone was rebooting every 3-5 minutes. And the battery only lasted for half a day (afterm3 years)
Repair was super easy. Did it while looking at the detailed photos ifixit provides. Everyone can do it. No need to give Apple 70 USD
It didn't fix my problem. I had to restore the phone in DFU mode. But my phone lasts for alsmost three days now!!