That would be bad. That would allow the full power supply to flow through the diode and into JP8 with unlimited current. Likely blowing out either the diode or the Kanalog Driver.

The original 0.3A supply might have been small enough not to cause any damage. But I don't see any way it could have worked.

The JP8 outputs are supposed to "pull" the JP8 pin voltage from 24V down to close to 0V so the solenoid "sees" 24V and turns on. If it is not pulling the pin voltage down to 0V it is likely damaged.