Sounds like the C-axis stepper driver direction input has stopped working as it's just stuck in one direction. If you can, measure the voltage at the direction pin of the C-axis stepper driver. If it doesn't change when you move the axis the other way then it's most likely a problem with the breakout board. If it does change then it looks like a problem with the driver. To check the driver try moving the input wires to a different driver and see if it works properly...

Have you got any spare outputs on the breakout board? If so you can use one of those for the direction input to C instead and just redefine it in the ports/pins settings. Probably easiest to try this first.