My Philips Avent Digital thermometer display is blank

The battery may have run out. Follow the instructions on how to replace the battery for your flexible tip thermometer.
Note: The battery of the soother thermometer cannot be replaced. If the battery is empty, discard the soother thermometer.

Replace the battery of the flexible tip thermometer as described below
1) Remove the battery compartment cover.
2) Use an insulated probe to remove the battery (e.g. a toothpick).
3) Insert a new battery (LR41) with the + pole facing upwards.
4) Reattach the battery compartment cover.
5) Dispose of the empty battery in the proper way.

Check that the measurement unit of the soother thermometer is firmly attached to the soother and completely locked into position, i.e. turned all the way to the 'closed lock' symbol.