The robot voice prompts "the water tray is not installed", what should I do?

1. Open the top cover, flip the power switch to "O";
2. Please slightly lift the the roller mop side;
3. Open the blue buckle of the water tray, remove the water tray, and check whether the magnet inside is still there;
4. If it is not lost, please install the water tray back to the bottom of the robot. A "click" sound means it is installed in place. Restart the machine and observe
5. If it is lost, please contact after-sales service.