Ignition OFF When Disconnecting Battery Caution
WARNING: This page is about a different car, the 2017 Chevrolet Spark. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Always turn the ignition OFF when connecting or disconnecting battery cables, battery chargers or jumper cables. Failing to do so may damage the Powertrain Control Module (PCM) or other electronic components.