I’m working on our own carrier board and so I’m studying your reference design. Is Q30 backwards on the carrier board? In the configuration now it would work and turn on with a positive voltage but it looks like the purpose was to provide reverse current protection? If so it looks upside down (simulation shows the same), so it would conduct current through the body diode if the reverse polarity was connected.
If that’s not what it’s for why is it there?
As a side note it would be nice to have a document that runs through the function of all the power pieces on the carrier board, there are a lot of moving parts there.