oral b charging light do not stop flashing

Have an Oral b type 3728.

Changed the battery.

Is charging and the blue light flashes.

The problem is that I do not know when it is fully charged as the flashing light is not changing to a steady light, as earlier.

What has gone wrong?

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0

crwdns2894050:0crwdne2894050:0

crwdns2889612:0crwdne2889612:0 0
crwdns2892346:0crwdne2892346:0