When beginning re assembly and reusing the backplate seal, a fair amount a heat with a hot hair gun helps to evenly reseal it.
You can save a step here by keeping the fingerprint scanner attached as long as the back plate is supported by a minor angle. You’ll detach the other side at the system board in step 7, at which point you can put the whole piece to the side.
You’ll also want to detach both two antennas here and note the specific wire and its position on your system’s board. The antennas on mine are closer together, making it easy to re-connect them to the wrong terminal.
This task needed a fair amount of heat, using both a heated pad (ifixit iOpener) and a hot air gun. Insulated gloves makes this step effortless. Heat both ends just near the adhesive until you think it’ s too hot to touch w/o your gloves, then gently pry the battery out using a long plastic spudger. I started on the right side, broke it free, then worked my way left. A hand held hot air gun here is perfect for this because the adhesive, at a good temperature, cleanly peels away from the battery and stays on the phone surface, making it perfect to reuse.
I just replaced a front assembly with the home button connector so stiffly attached that the tab to the left of it broke off while trying to lift it. This happened while resting the display on a very hot iOpener. Some phones simply have a much stronger adhesive. My only advice is to gently prod at the connector from the left with the sharp pointy end of a spudger until it eventually comes lose. In this situation, I was eventually able to lift the connector off undamaged, but I feel like it could've been easier the way you've mentioned, by keeping the two parts of the connector together!
+1 for a photo showing the correct layering and routing of cables. I accidentally routed the home button ribbon above the digitizer ribbon and beneath the power and backlight ribbons. The uneven pressure it put on the digitizer connector after tightening the plate caused my digitizer to not recognize touching the display or made touches appear off center.
This was by far the hardest part of the repair for me. Getting leverage while finding a way to prod with a spudger is a challenge in coordination. I used a second spudger with point holding the phone down by the headphone jack, with the other end of the spudger anchored to my desk.