My convection oven began to beep and F-1 message appeared. We turned it off and turn it on again. It then worked fine. The next day we attempted to turn it on but it would not. However, the oven light and clock work. We turn the breaker box on and off a few times but the oven would not work. The model number is W156W. Can you tell me what the problem is and where I could purchase the replacement part, if necessary.

Thanks