Magellan Echo Series User Manual page 12

Note: The battery lifetime depends on usage of the Echo watch
(calculations have been done on 12h non connected usage + 1h/
day workout).
To replace the CR2032 battery, simply open the battery lid at the
back of the watch.
Replace the battery with the POSITIVE side up and place the battery
lid back in place.
Note: After replacing the battery, make sure that the O-ring is
seated properly into the groove before closing the battery lid.
Note: When closing the battery lid, make sure that the lid fits
properly on all corners and then press to lock the lid in place with a
click sound.
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