Check the fuse. Also check out the safety switch by the unit door. If not closed when door is closed, no power is applied to either the turntable or the tube.
A thermal protector on the magnetron may have opened. Normally, these reset within a few minutes. If you've had the oven off for more than an hour, and it's still lifeless, then you may have a bad connection somewhere. A defective magnetron will not cause an oven to be dead if the main fuse has been replaced - at least not immediately. If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_29ad5d1dd86564b0
Try removing the power plug from the wall, wait 30 seconds, plug it back in, and then try again. If it still does not work, then you will need to take it to a local repair shop, as there is nothing further you can do
Quite often this is due to grease or food particles stuck somewhere in the cavity of the oven or stuck on or behind the waveguide cover.
It may also be in the area of the turntable support, coupler, or motor.