Walgreens WGNBPW-720 Manual page 14

Replace the batteries if:
switched on.
As the supplied batteries are for test only, they may be
discharged earlier than batteries you buy in stores. Replace
all batteries at one time (as simultaneous set). Use only
will need to be reset if batteries are removed or replaced.
Clean contacts on battery and in battery compartment with
a soft dry cloth each time you install batteries.
Note:
together with the household garbage.
13