NGM Facile IDEA Guide Rapide page 26

Inserting the Battery: your device is provided with a lithium-ion
battery and is designed to be used exclusively with original NGM
batteries and chargers. The battery must be inserted into the
backside of the phone. Insert the battery into the battery
compartment with the contacts facing up, matching those of the
phone. When done, put the hind cover back into position as
shown in the following illustrations.
Inserting the battery
Placement of the cover
26 ENGLISH