It possible that a spike from the stepper drivers may have damaged the UC100.  Please keep in mind that modern stepper drivers in order to improve performance and generate very high voltage spikes.  It is the high voltage that saturates the driver the coils of the motors quickly.   These also translate into electrical noise that can affect the PC, motion controller, breakout board and other electronics.  For this reason, stepper drivers are optoisolated.  It is very common for users to voluntarily or involuntarily connect the negative of the power supply powering the drivers to the ground and the negative of the breakout board/motion controller to the same ground creating a ground loop.  It is important to verify the negative of the breakout board is isolated from the negative of the main power supply.  This video explains it a little better: https://www.youtube.com/watch?v=r_BNxS02nKg

Other possible solutions are upgrading to an Ethernet Motion Controller like the UC300ETH or implement a C83 which will isolate the breakout board.

If you still have questions regarding this, please feel free to request support on our website: https://www.cnc4pc.com/contact/