Danfoss RET2000 B Mode D'emploi page 10

Low Battery Indications
When the batteries require replacement the battery low symbol
GB GB
will flash. Batteries should be replaced within 15 days, after
which the thermostat will turn off the load it is controlling. If
ES
the display does not illuminate the batteries may have expired
and should be replaced immediately to avoid damage to the
thermostat
FR
10 RET2000