Normally, I would just throw it out and buy a new one but it's a fairly new microwave And at the moment I don't have any extra money at all so I'm stuck with it for now. Also, it's my main method of cooking food. A few days ago I was microwaving something for only one minute and a small piece of food I didn't know was in there caught on fire, which then set the plastic ring on fire... That part was scary enough but it also started making a weird buzzing sound.

I cleaned the microwave and tried using it again for 1 minute, it buzz for a second but then seem to work okay

I tried one more time to use it for popcorn and it worked, but I've been too afraid to use it ever since.

Is there any surefire way to test if it's still safe? What would cause the buzzing along with a fire? I'm also surprised that the food cut on fire so quickly since it was only for 1 minute cook time.

I don't know the exact model, but it's a GE over the range microwave That's just over a year old, so of course there's no longer a warranty.