In most cases, this might be caused by a faulty limit switch. Troubleshoot by the steps below.

1. Remove the glass cover on the left side of the engraver.
2. Remove the metal plate on top of the main board.
3. Check the status of LED1 and LED3 on the main board.

Under normal circumstances, LED1 and LED3 will light up when the laser head returns to its origin along the X and Y axes, go out, then light up again, and finally go out.

If LED1 (or LED3) is always on, then the limit switch of the X-axis (or Y-axis) (as shown) is faulty or malfunctioning. You can fix it by simply giving it a gentle tap or replacing it with a new, identical one.