I have both the Xtool D1 and S1. The fire button works as expected on the D1 as it toggles the laser on and off with button press. On my S1, the laser fires (red around fire button on), but second press (red around fire button off) but the laser does not turn off. I have to open the lid to force the laser to stop firing,
FYI, observing the same behavior when device is set to allow fire when framing or “Shift” + “Frame”. Laser fires during framing but does not turn off after framing is complete. Must open lid to turn laser off.