Hello,
For the issue of the device falling down stairs, we recommend checking if dirt is covering the bottom cliff sensors, which might cause them to malfunction.
If the cliff sensors are not obstructed, please ensure that the virtual wall feature is set up at the edge of the stairs, positioned away from the stair edge to prevent this issue from occurring.
We advise you to provide our customer service team with the purchase invoice of the robot and the S/N number found on the robot's bottom label. Once we receive the information you provided, our customer service will offer further assistance.
https://www.mova.tech/pages/contact-us