RE: Futaba R124F
If you plug a regular battery into your receiver, and do not plug in the speed control, does the system still work? If so, then something in the speed control is affecting how the receiver works. It's also possible that there's something wrong in the receiver. It may have been partially-damaged in the prior crash and then finally gone off when you re-connected the new components.
You can never tell what the results will be when you have a crashed system.