Completed this battery replacement on my iPhone 6 on Saturday, overall it went great and my phone works so much better, as the old battery was completely dead basically.
A couple of points from my replacement:
1. I didn’t remove the display, to me that seemed like a greater risk of damaging something, i supported the display with a box and it worked great.
2. watch the video guide especially around removing the adhesive strips, they show a different procedure there for the actual removal and that worked great for me compared to what the images show above.
3. the ribbon cable on the new battery is certainly not formed as accurately as the OEM battery and required some wrestling to get it into place and to connect and to get the connector cover back on.
Overall its a great How To and definitely a trust worthy place to buy quality parts and I enjoyed the DIY side of it.
Though with apples new lower price, I’d just take it there if I had the time over, I saw their new price within an hour of finishing my install off.