Parts layout & wiring has made a lot of progress. Power switch is working. The halves still close.

In the pic below:

• button/speaker
• audio amp
• pager motor
• battery
• Using the LED common connections on the old main/switch board as a power bus.
• charger is beneath the switch board
• dual FET for main power switch and pager motor
• battery door space for: RTC, accelerometer, external USB connector
• RPI Zero (USB power, data, and SDIO wiring visible, other connections on the other side)
• ESP8266 for SDIO WiFi
• audio and button connectors, LED power