"The model was recently involved in a crash but I don't want to just to conclusions that THAT is the cause of the radio problems."

I'll jump to that conclusion. If the radio functioned properly (with adequately charged batteries) before the crash, and now doesn't function properly, then it was damaged in the crash. Send the RX and TX off to be checked. Check the switch, too. Check the battery pack, was it damaged (dented or distorted)?

DON'T RISK YOUR PLANE!

Dr.1