One day all the suden i noticed that the stove had an F1 on the screen... i don't use the oven very much so i didn't pay attention to it. Then one day when i tryed to use the oven it wouldn't let me and F1 kept poping up on the screen... i really want to use my oven but it doesn't get hot... and I don't even know what F1 means and i don't have the manual for it. can anyone please, please, please help me out here and tell me if there's anything i can do to fix it. thanks!!!!