Kenmore 1200W countertop microwave oven, manufactured in 2012, in use continuously since then.
The internal light and turntable do not turn off when the door is opened, which indicates a broken door sensor.
It's not clear to me if the microwave emitter shuts off when the door is opened.
Otherwise, the oven is clean and works fine.
The sensor could be replaced. You must be familiar with microwave oven repair. Certain components in the oven are very dangerous to touch, even if the oven has been off for a long time.