1. Adjust both the maximum and minimum power to 100%.
2. Turn the knob on the ammeter to its maximum.

If no laser is being fired, check whether the "water protection" on the  LCD reads "on".

If it reads "off", 

• Check whether the cover is  closed
• Check whether the debris tray is fully inserted.
• Check whether the coolant flow is normal.

If all these have been proved normal, 

1. Short-circuit the cover interlock and debris tray interlock.
2. Check the "water protection" on the  LCD.

If it reads "on", then the interlocks are faulty. Replace them with new, identical ones,

If the problem persists, short-circuit this port on the laser power supply (as shown).

Check the "water protection" on the  LCD.

• If it now reads "on", replace the sensor of the water protection. 
• If it still reads "off", replace the laser power supply.