How can I check the battery level in the remote control?

       Press the ‘beep’ button on the remote control:
-A single red light appears at the top of the remote control: the batteries are working correctly
-Several flashes of light appear at the top of the remote control: the batteries are low, they must be replaced soon (warning)
-No red light appears at the top of the remote control: the batteries have worn out, replace with new Martin Sellier batteries of the same type.