Based on information in the Mantis Q manual:
*If you have good GPS lock and adequate battery, the Q will return to the last recorded home point.
*IF you don't have good GPS, the Q will drift in the wind until it runs out of battery, and will then land wherever it happens to be.
*If battery level reaches 5% decreasing, it will land wherever it happens to be, whether it is drifting in the wind or trying to return home.
Upload your flight logs. Maybe we can at least give you it's last known position.