[] Red when first powered on.
[] Blue LED for on but not connected to/hosting wifi.
[] Green LED for on and connected to/hosting wifi.
[] Low power sleep between main loops, waking up from PIT interrupt
[] Power on RPi when RTC alarm triggers.
[] Power off RPi after 30 seconds when requested.
[] Long button press restart ATtiny1616
[] Short button press trigger RPi to enable wifi again/wake up RPi.
[] Power off RPi with low battery voltage.
[] Power on RPi when battery voltage is normal again.
[] Read battery voltage.
[] Read RTC battery voltage.
[] Each of these errors triggering a flag in the I2C register. [] Each having a unique LED flash sequence. [] Wake up RPi when RTC alarm didn't trigger for 24 hours.