This message can have several causes:
1 / The battery level of Door Keeper is insufficient. It then needs to be recharged.
2 / The battery level of the badge reader / keyboard is insufficient. In this case, the batteries need to be replaced (as a reminder, the reader requires 3 AAA LR3 batteries).
3 / The product has been exchanged:
a) If the reader is replaced by another one, make sure to turn off the old reader and remove the batteries before installing the new one.
b) The reader has already been installed on another Door Keeper. To pair it, it is necessary to perform a keyboard reset.