first of all I see no mention of a failsafe which is needed with any nitro car... Would have prevented your runaway.... 2nd problem is your radio and receiver.... Just replace it ..... If you did any research at all, you would no that the radio/receiver is the weak link in the cen product line.... Cen will most certainly replace the original for you, but you will most likely have the same problem...
Thankfully the cars are tough... I have the mt2 and have had the same issues along with most everyone else... I replaced the radio system and have not had a single problem since..
My first transmitter lasted about a day before it reversed itself and died... The receiver lasted about a month before just dying....