MarkT:
You need to check:
- Battery pack voltage isn't drooping significantly under load.
- Those hookup wires are able to handle the current (some are only rated for signals, not power)
- That your dirpin signal is making it onto the DRV8825 board (use a multimeter).
The battery pack voltage is dropping under load, this is an issue but I don't believe the one causing the motor to not rotate both ways. My group is looking into alternative ways to power the motor within the rules of the design project.
I think you may be on to something on the hookup wires, I just got them out of my roommate's electrical pack. I'm going to try to switch up the wires later today and see if anything changes. I will also use a multimeter to check the dirpin signal. Thanks for the help.