Disassembly and reassembly went well and quickly… however…
When I plugged in my old iPhone (hard restart), it already claimed 61% even with a brand new battery. It also thought it was 6 years in the past, and couldn't sync with any wifi signal. I re-installed my old broken battery, and everything was back to normal. So I re-re-installed my fancy new battery and: 61%, December 31, 2012 on the calendar, and no wifi. Also, I can't unplug it, or it dies, even after 4 hours on the charger. I think I might have wasted $25.