Hi, welcome to Just answer .... it seems the power board has failed and will need replacement ... the cost of repair will be around £140________________________________________________________________________________________If you have further questions I will be pleased to assist you .. Please remember to RATE my answer Excellent or Good Service when you are satisfied....Thanks
Please tell me its complete model number and how old is it ? how good are your DIY skills ?
Leave the microwave unplugged for few hours ... I do not recommend anyone with appropriate DIY skills to work on these as it has high voltage even when turned off ... check this image part#1615 or part#1655 will have to be replaced ... if the repair cost is more than the cost of new one ... it is better to go with new one