looking at your photos
I can not see any wires between the MPG and a 5V power supply !
the MPG does not have a direction output so you will need to detect the change from the A & B channels
for a very simple test without using a quadrature decoder circuit to generate the Direction signal
you could connect the MPG to a 5V supply and us the A+ to provide the step signal
and use a toggle switch to control the motor direction
John