Microwave is not working

broken or misaligned door interlock switch is most likely

Bad Door switch, back feeding power to turn table motor circuit

The switch assembly is somehow staying "closed" satisfying the interlock and enabling it to run.
Disassemble the unit, beware specially of the high voltage capacitor, if you aren't comfortable or competent, buy a new microwave. If you are mechanically inclined, disassemble the unit until the switch assembly is accessible; it will have the door latch attached to it.
The switch is either broken or something? exogenous is keeping it closed. It may have come loose due to the door slamming?.
It's a simple fix. I am certainl you will be successful.

Check three door sensors, especially for two closed state switches.

hi,
there is a micro switch that signals when the door is closed. this tells the machine that it's okay to start the turntable and heating process.. if the micro switch breaks or shorts out then the switch does not send the signal so the machine does not work.
hank

We recommend you have the microwave evaluated by an authorized service center.

Authorized service centers can be located in the below link.

www.panasonic.com/repair

there's a ghost in your microwave, call ghost buster. Seriously, the problem is the control panel. (((((the microwave oven can store thousands of volts of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. That's more than 30 wall outlets combined.
Replacing electronic parts in a microwave oven can be extremely dangerous.))))))) tank you
Samsung Model SMH1816S XAC Parts

Its likely beeping as it is not heating, I presume light goes out when door closed and a turntable turns or not?

I can provide possible reasons for no heating etc.

It is one of two things, faulty door switch, or the keypad control board.

Sounds like a door switch problem or stuck relay contacts on the control PCB. Do the light and fan run too or just the T/T??