Interested to know what the problem was - when you sort it !
My vampire died first meeting out - but I still had power to reciever and servo - just no power to motor. Speedo just blinked and would not respond to anything or to being reset.
Speedo was faulty and was swopped for another - fingers crossed no problems so far and it's running great,
Hope you get it sorted
Sounds like it could be something other than the speedo though - radio / reciever ?