If its one of those horrible membrane type switch panels you are probably looking at raplacing the panel - if you gan get the part. (Try Espares or Ransom spares).
For the price of a new low-cost microwave, go to someone like John Lewis and get one with a 2 year warranty.
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February 2015
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howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix microwaves.