Geeetech

If i start my printer it will start heating automaticly to 300+ degrese .
it will by problem with mosfet. So i have an idea connet it like second extruder where mosfet maybe will be ok.
how i must set and do ? Connect heater , temp and fan to second position and edit code in arduino ? or what ? thank for help

main board is GT2560 rev a+

I found the problem. The manufacturer had grounded one lead of the thermocouple and, additionally jcpenney login, the electrical connection for it was loose. The temperature is now proper.