I would open up the transmitter ans search around for a fuse. It may be blown.

If that doesn't work, remove the battery, plug in the charger (be sure the transmitter is off) and check the leads that the battery plugs into to see if there is a current coming in from the charger. If you don't have a volt meter, pick up a cheap one from your LHS or Radio Shack - it'll always come in handy.