running, not cooking anything you put in it

alicemurtagh , The problem could be a few things a faulty diode,transformer, magnetron, etc.. Since this can be one of the most dangerous appliances to work on, it would be best to have a qualified appliance repair Technician have a look, diagnose and estimate repair. Link below provides some good info.. Good luck.

I hope this helped you out, if so let me know by pressing the helpful button.

https://www.repairclinic.com/RepairHelp/...

Most microwaves have a fuse. Check the fuse for continuity. Sometimes the cavity magnetron which creates the Heat to cook the food will go bad. Most magnetrons have a two prong female plug the male ends are on the magnetron you can check with a meter for continuity from the case to each one of these and also prong to prong open circuit definitely indicates a problem. Getting ahead of myself I would definitely check capacitor which is a short-term storage device for electricity to give the necessary boost current to get a magnetron going. Of course if you don't have any spare microwaves laying around, all you're going to be able to do is check the fuse and check the rest, because if you are like me, you just have to find the problem. Please unplug the microwave before Servicing. If you are not experienced with anything more technical than changing fuses, I would not recommend any further testing. just go buy a microwave.