Hello friend
I had the same problem and solved almost,
PCB in the plane of board indicates that a regulator IC2, MC33269ST-3.3T3
But as shown this is 3.3V, I replace with a similar AMS1117 3.3V SOT223, and works partially because the card requires 5V, and buy AMS1117 5V SOT223 I'm waiting for it to arrive.
my apologies for the Spanish to English translation
and the other question is positive ic2 regulated 5V to power the board from the power and remove the USB.
regards
I had the same problem and solved almost,
PCB in the plane of board indicates that a regulator IC2, MC33269ST-3.3T3
But as shown this is 3.3V, I replace with a similar AMS1117 3.3V SOT223, and works partially because the card requires 5V, and buy AMS1117 5V SOT223 I'm waiting for it to arrive.
my apologies for the Spanish to English translation
and the other question is positive ic2 regulated 5V to power the board from the power and remove the USB.
regards