Looks like the debug UART of J1 is wired to the CP2102N in the picture. That’s connected to the USB-C port, but kept in reset state by R88 (10k pull-down). Strapping it up to VCC by shorting R86 (or connecting TP5 to 3.3V) seems to enable the device… that gives debug logs on the USB port with the device in the box. 
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