Troubleshooting an example motor board - how?

Adding to the above, the 10K resistor controls how much current comes from the pin. 5V / 10,000ohms = .5 milliamps.

.5ma also seems very low; per the p2n2222ag datasheet that's only ~150hfe, so only .5ma * 150hfe = 75ma that will flow through the transistor. Do you have any lower value transistor (200 ohm minimum) that you can use?