20 - 30 minutos
iPhone would randomly shut off even after battery was fully charged.
Repair took about 25 minutes. Step by step guide was excellent. Was able to remove the screen, logic board and old battery. Put in the new battery and then put back the logic board and screen. Charged the battery for 24 hours and now the iPhone works amazing. No more random shutdowns! Thank you ifixit !!
Take your time and read all the instructions. You're dealing with delicate parts, so need to be patient in order to do it properly without damaging any parts.