Hi Andrew,
There is a very remote possibilty that pulling the power, waiting one minute and then reconnecting could clear a glitch, otherwise this would indicate that your microwave has developed a fault with the control circuit board which would require replacement of this part. Bear in mind the cost of this part would be close to the cost of a brand new microwave, so I'd suggest that you'd be better off cutting your losses now and replace this faulty oven with a new one. The only exception being if it is still under warrenty or you have a repair insurance poilcy.
Rupert, June 2020
