Yamaha Revolabs FLX2 System Manual page 52

Dialer
The battery in the dialer can be exchanged after the dialer's back was opened. The
back of the dialer opens if pressure is applied, pushing it back away from the charger
port and lift it, as shown in the picture.
Take the current battery out of the handset as shown,
and replace it with the new battery. Please ensure
that the connectors on the battery are lined up with the
connectors inside the dialer.
Speaker
To change the rechargeable battery in the FLX speaker you will need to use a
screwdriver to loosen the screw on the bottom of the speaker.
Once the screw is loose, the bottom door of the speaker will open, revealing the
rechargeable battery pack. Carefully take this battery pack out of the speaker
enclosure, unplugging the wire.
Plug the new replaceable battery into the connector, and place it into the speaker. Close
the door, and re-tighten the screw.
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