Check the connections between the Ruida and the power supply. They should be:
| Ruida | Supply |
|---|---|
| L-ON | TL |
| L-PWM | IN |
| G | G |
By default, Ruida uses an active-low signal to fire the laser, which would connect to TL on the supply. There is a setting in the laser area of the Machine Settings (near the bottom) that sets whether it’s active high or active low.