Big Futaba 3vcs mistake

[jaffacake]

Bit reluctant to write this post as it really shows how stupid i have been
I recently bought a 2nd hand really nice condition Futaba 3vcs transmitter in 40 meg
Im expecting a 2.4 module for it in the next couple of days, so after getting to grips with the menu etc i thought i would change the modulation setting from ppm to pcm mode in readiness for the 2.4 module, but in doing so the 40 meg module got very warm & now the transmitter wont turn off unless i disconnect the battery pack at the rear
I can still scroll through menu's etc but not turn the tranny off using the on/off switch
Is it knackered or is there any bright spark out there that may have a solution? Or is it now just a trophy to my stupidity.