No, there is nothing displayed that tells you the batteries are being charged. Make sure you are using the yellow battery holder or they won't charge. Also make sure your charger is of the correct voltage and current to charge the batteries as well.
There are a couple of signs that the external power source is working. First, the battery low level indicator will stop flashing and beeping. Secondly, and this will let you know things are working, the radio around the battery holder will be slightly warm. This is normal. If it is hot to the touch (i.e., could cause a burn), then disconnect the charger and test the radio with fresh batteries. There could be a problem with the charger or charging circuit.
The best thing you can do for charging though is to remove the batteries and use and external charger. The chances of something malfunctioning are pretty slim, but if it does, the radio is probably going to be history.