Hisense RS723N4WC1 User's Operation Manual page 11

11
When cooling a full freezer of unfrozen
food the superfreezer function will take
around 24 hours to fully freeze all food
items completely.
If the appliance has not been
used for a while and is switched on, it is
normal for the alarm to sound. Please
deactivate the alarm by pressing the
"Alarm" button.