When the robot is in cleaning cycle or has finished cleaning and is still in the pool, you can use the return tool to recall it. The return stick emits a sonar signal that wakes up the robot, prompting it to move toward the signal source and climb to the pool wall, where it will pause near the waterline for about 5 minutes so you can easily retrieve it.
If the return tool does not work properly, it may be because the robot is too far away, causing the signal to be too weak to reach it, or because poor water conditions are interfering with the sonar signal and reducing its effectiveness.