A DAC overflow means that the control commanded a move but did not see it. If the encoders are not counting (with the motor moving) then you will still get the DAC overflow.
The encoders need 5 VDC to count which comes from the logic power supply, through the mother board , through the BMDC (through L1 on the BMDC) to the AXSBOB to the encoders. If both do not count, typically it means that the L1 has blown as it acts as a fuse against excessive current such as a direct short when a encoder or wire suffers damage.
Hence, I believe we have cause and effect here with some certainty. You could remove the BMDC and check L1 for continuity with a digital meter.