Bob, The receiver should have a cable from the receiver battery pack going into it OR not if one of the speed controllers is being used as a battery elimination circuit, in which case the speed controller will provide the power through the throttle channel and an on/off switch will be built into that speed controller. I assume the two speed controllers are controlled through a "Y" cable from the throttle connection, You say rudder servos so I am assuming there are two rudders which, again, I assume will be operated via a "Y" lead to the two servos.
I would approach it from the bottom of the ladder and go up step by step only after you have proved the step you are on is OK.
1) First turn on the transmitter, if it has a battery level indicator is it reading OK? If not change the batteries anyway just to be sure.
2) Turn on the model, if it is 2.4 does the receiver light up? If not try binding it again. If 40 mhz check both crystals are the same number. Are there leds on the speed controllers, do they light up as normal?
3) If the receiver has its own battery put fresh batteries in anyway. If it uses a battery elimination circuit it will not have a seperate battery pack.
4) Charge up the main power battery and be sure this is fully charged. If unsure replace it with one that you know is fully charged. Models left for a long time can have completely dead batteries that will simply not charge. If your receiver uses a battery elimination circuit then a flat main battery could give you the symptoms you are seeing.
If there is beeping things are turned on so it is not a hidden switch that is the problem. I also would not get involved with the speed controllers or brushless motors as this seems to be far more basic than that.
If you are still getting nowhere perhaps you could list the equipment you are using so we know what we are dealing with. Make and number of transmitter, make, type and number of the receiver, make and type of speed controllers etc…
Edited By Richard Simpson on 14/10/2021 09:38:08