It was disappointing to find that the ARM was bad.  VCAP went only to 0.5V & it wouldn't boot.  Shorting it to VDD got it to start.  Reflowing it a few times got it to 1.2V but it still wouldn't boot.  Hopefully, it was a solder ball, but the ARM was replaced with a working chip.  It's a big deal when an STM32F4 dies because they're still $10 a piece, to this day.  A whole raspberry pi is less, but it doesn't have triple I2S ports.

The complete PI section was attached.  Another high voltage lead is required for the preamp.  The 24 bit vlogging mic was cannibalized.