Etymotic The BEAN® Quiet Sound Amplifier® - Manual (Page 5)

BATTERY INSERTION
4
The battery must be inserted correctly
or the QSA will not work.
1. The battery compartment is located
on the underside of the QSA.
2. Open the battery door.
3. Remove the yellow tab from the battery.
4. Insert the battery with the flat side
facing up.
5. Do not force the battery into the door.
Battery
Compartment
#10 Battery
Inserted
Battery
Door
Note: The door will not close
if the battery is not inserted correctly.