Great little guide! I’ve just had to replace the second battery on my 6S Plus, and because the aftermarket sticky strips that secure the battery to the case where less sticky (not from iFixit), it was possible to skip steps 17-27 (but perhaps not advised) turned into a 5 mins job all in as opposed to nearly 40mins because the original battery sticky strips are a really pain! Regarding the perimeter tape gaskit that seals the screen to the back, it is possible to reuse the original but it is likely to part lifted / broken. So I’d say that dust protection is compromised, that said, I still found the orginal gaskit adequate even after two battery replacements . GearDo via aution site in the UK offered the gasket as a separate item, but I’ll save it for my 3rd battery - haha!