Power Button Not Turning Device Back On
The power button no longer turns the device back on after the PMIC is shut down (this worked on kernel 5.3.0-g8908ba21).
I can tell that BUCK6 (VDD_3V3) is turning on when the power button is pressed because the red LED becomes illuminated after pressing it but it does not bring up the SoC. This means the issue is likely has something to do with how the PMIC is configured to handle the button press events in one of its I2C registers (e.g. something like C1_SHORT_PUSH_EN, C1_LONG_PUSH_EN, etc).
The workaround for this issue is to press and hold the power button for 15-18 seconds or so in order to cause the BQ25895 charge controller to hard-reset the entire device.