I had this happen to my TK-40 but it end up not being a problem with it. What kind of transmitter and receiver are you using? It turned out it mine was a problem with the binding of my Flysky FS-i6 TX and RX. I rebound them and it worked again. When I fired up the radio it couldn't show me the status of the receiver so that was a dead giveaway it wasn't talking to it.