Durango Overheat

My car has been overheating for the past two weeks. The thermostat was replaced and it worked fine for one day. What I have been doing to "fix it" when I am in a hurry to take the radiator cap off so that the pressure can go down, then I turn the water on so that it fills the radiator and at the same time cools it. I was told to turn on the heater so that it can suck more water in and make sure it works.

Well today was the day that it really overheated and I was in the middle of nowhere so I just took the cap off so the pressure would go down but didn't have any water to cool it down. My friend told me that since I didn't cool it down then the motor is probably stuck and that it will not work anymore. Is this true?

And if the motor is still okay, what can be the problem since the thermostat has already been replaced?

Thanks for your help!!

are you losing coolant???.. check you fan clutch operation!!