That's a great photo, thanks for that. I wish all posters could take such good photos.
But we're still guessing without knowing the other side of the PCB and being able to see the vias and traces (or internal traces).
At this point my guess is that it is a FET that switches the incoming power. Probably a "smart diode" using a FET as a diode to protect the device against reverse polarity connection;
The reverse side of the board has nothing on it where those components are. Theres a surface copper layer but it has no traces. It must all be connected with a mid layer :/
I think you're probably right though after doing a bit of research on FETs. Having trouble finding the manufacture of that particular component though, Vishay make FETs with a 0.8x0.8mm footprint but the connections are almost BGA-like whereas the one in the photo is soldered from the side.
Would you say the pin labeled G is probably the gate? Which would make B and A source pins and the dot the drain. Although the dot could also signify pin 1, would the drain usually be considered pin 1?