I have a sharp microwave / convection oven. It only runs for 59 seconds at a time. How do I fix this?

I have a flaky Sharp too. Microwave ovens are so cheap these days, the most cost effective way to fix it is to simply get a new one. But avoid Sharp. Every Sharp product I bought had problems within a few years. Not just microwaves, but everything of that brand, including calculators. My flaky Sharp microwave has flaky sensors to sense the door being closed, so it sometimes stops as if the door were open, and sometimes won't start unless I jiggle the door latches. A Sharp microwave I had in the past had a different problem.

On the other hand, now that I think about it, I can't think of any brand of microwave I ever had that was really reliable for more than a couple of years. But since they're so cheap, it's no big deal to get a new one everytime the old one starts having problems.