WARNING: This page is about a different car, the 2023 BMW X5, 2022 BMW X5, 2021 BMW X5, 2020 BMW X5, and 2019 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
Fold up the luggage compartment floor covering (1).
Release the expanding rivets (arrows) and remove the battery cover (2).