What is indicated by a flashing black hourglass on an AED FR2?

A flashing black hourglass icon on an AED FR2 specifically indicates that a battery insertion test is required. This symbol signals that the device has detected an issue with the battery's connection or its status, prompting the operator to check the battery to ensure it is securely installed and functioning correctly. Addressing this indication is vital because it ensures that the AED is ready for use in an emergency situation.

In contrast, a steady or different icon would signify that the device is operating normally or that the battery is low or requires replacement, which does not align with the specific meaning of the flashing hourglass icon. Recognizing and responding to these indicators properly is crucial for maintaining the AED's operational readiness.