Upgraded heat pad and almost set my house on fire

I upgraded heat pad to 120V 300W

Started the print, termistor detached, heater went into ON untill i noticed smoke coming from the bed smoking bottom coating.

If termistor did not detach, i still cant guarantee it will not brake.
Is there a fail safe mechanism i can use to make sure print stops if termistor brakes ?

I know there is a stop in the firmware for the hotend, but is there the same stop in the firmware for the bed ?
Thanks !

EDIT:
I tried to pull the termistor from the board while it was NOT heating the bed because required temp was reached.
I tried to pull the termistor from the board while it WAS heating up to reach required temp.
In both cases print did not stop, as well as in both cases heat did not go up while print continued to go on.

Conclusion:
If termistor fails to read/brakes/wire disconnect, it will not stop the print, it will simply not heat the bed.
If termistor works but got detached, DISASTER will take place.

Most important conclusion:
Termistor MUST BE ATTACHED to the pad using [automotive gasket maker] such as "Permatex"
Detached termistor will make printer continuously heat up the bed because termistor is still reading the temperature and because of its lack of contact, its too low, so it continues to heat