Q: The RDY indicating light is off on DY3E stepper driver, the CNC lathe is using GSK 928 TC, what happened?

A: The RDY light is not on means the DY3E stepper driver is broken, need to be sent back for repair or replace a new one. 

Same result for DY3A and DY3F.

DY3E Stepper Driver Specification and User Manual