Your initial hookup was quite jumbled. How is it connected now? The dual H-bridge board has the inputs paired on either side of each enable. That is, Inputs 1 and 2 go with Enable A for Motor 1, Inputs 3 and 4 go with Enable B for Motor 2.
If your motor is connected to Motor 2, you should have your Arduiino outputs connected to Motor Driver pins as follows: 9 to 4, 7 and 8 to 3 and 5 (or 5 and 3, no difference. You MUST have the grounds on the motor driver and Arduino connected. Also, I noticed that your code would run the motor at full speed for ten seconds, then try to reverse the direction without slowing or stopping. This is asking for trouble. You should take the enablePin low, change 7 and 8, then take enablePin high again, then take it low again at the end of your loop.