Yesterday, after removing food from my microwave and closing the door, it continued to run. No light on inside, turntable not spinning but it was running as if I had programmed in more time. I unplugged it for 10 minutes and replugged it back in and again, it is running while the timer is showing 0. I put a full cup of water in it and allowed it to run without programming it and it heated my water to the boiling point. I have obviously kept it unplugged as this would cause a fire and I spoke with customer service. Apparently this microwave is 8 years old- I did not purchase it 8 years ago but it was manufactured in 2012. I was told Samsung would pay one-time for a repair person to come out and diagnose the problem but to cost of the repair would be on me. I have seen other posts regarding other Samsung models doing the exact same thing I am describing and apparently they haven't fixed the problem and have not recalled the microwave itself. Had this happened to my children, I don't know that they would have known to unplug to unit and fear they would have let it run causing a possible house fire. If I do not receive the repair at Samsung's expense or a new microwave, this issue will be brought forward to the public to try to protect others that have this microwave in their homes. Please be warned and check your model numbers.
I would like to look into this further. Can I have your full model code and serial number via private message?
UPDATE: The service technician came today and repaired my microwave. He replaced the main board and it solved the issue. Samsung paid for the service call and the parts. I am so impressed with their response and customer service.