Hi, first the Gypsies warning. Attempting repairs can be dangerous.
In many instances work should only be undertaken by a qualified professional. ok so as to the cause of the problem. All microwave ovens are capable of serious injury so in order to keep you safe they have their own internal safety sytems. Most often a complete power failure is due to the machine having blown its safety monitor fuse. Usual cause faulty safety interlock switches. (door switches activated by the door hooks) usually a job for a tech. Not a place for the untrained. For any further help or advice please feel free contact me via microwave-repairs.co.uk
kindest regards
patrick, July 2009