Re-assembly note -

Getting the battery to connect to the charging cable was a challenge for me. However, once it’s connected, if there’s any juice in the battery or if you want to be brave and plug it in, you can test to see if the phone is receiving power by trying to start it up and seeing if it vibrates. The combination of gently adjusting the charging cable, testing power, testing power with the phone plugged in got me to identify when the cable was attached properly.

Using my squishy finger worked better for re-attaching that cable than using the spudger.

This is a much better place to test for power than continuing reassembly and finding out it doesn’t work. If the phone cables are connected correctly and the battery has power (mine shipped with some charge in it), the phone will vibrate when you hold power.