If you have used a esc (speed controller) to power your receivers providing they have a Bec system then they shouldn't have fried....
My only conclusion is that the esc you used isn't capable of powering the reciver unit, in which case no power have been delivered to the reciver to fry it in the first place....
To which I can only support previous suggestions to power the reciver separately, either with a Bec unit or more commonly (and cheaper option) plug in a 4 AA power pack directly.
Before you do that I would suggest checking your esc to ensure it hasn't got a 5-6v Bec circuit built in as if it has and you have also powered the reciver with a separate power supply without disconnecting the esc's central ( usually red) wire from the plug then that would be the only cause for frying the reciver with an overload of voltage.
What esc are you using (make/model & amp range... e.g. Mtronics 15)?
And how are you powering your smoke machine? (Direct battery connection/ through the reciver?)
I'll draw up a wiring diagram in a moment when I log on my laptop with a suggested electrical setup which should stop some of the issues your having and give you fail safe running.
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