What does a blinking/static light with the label "CHARGE" mean? "Charging" or "done"?
It could be trying to get your attention when you can remove the charged battery.
It could be telling you that it's currently charging because something is happening.
But which is it?
There does not seem to be a dedicated manual for the battery charger.
The following excerpt is from a random Nikon camera user manual (PDF):
Insert the battery into the battery charger by sliding the battery forward and press down until it locks into place.