AGFA 307 Owner's Manual page 28

If no data appears in the data panel, replace the battery or check that
it is inserted correctly.
The 2CR5 lithium battery supplies power for camera function (auto-
focus, auto-exposure, etc.). The NP-500H rechargeable lithium ion
battery supplies the power for recording and playback of digital
images taken by ACTIONCAM.
When the power of one battery is extremely low (blinking low battery symbol
appears alone in the data panel), the ACTIONCAM will not function even if
the other battery has a full charge.
Chapter 1 Basic operation Battery Condition Indicator