You may have activated the crash inertia sensor, which will operate the hazards and unlock the doors, if they are locked. Switching off-on-off the ignition to reset, unless it was the alarm and you had a sounder operating as well, then if so u have a problem..
The info is in the owners handbook.
More info on what's wrong with your heater required, how many do you have ? as u say "heaters in the cab do not work"