You take to someone who understands what they are doing and is competent to work on it.
That is especially important if it is a commercial model, in a kitchen used by employees. You really REALLY do not want to risk the life of an employee by a DIY repair by someone with no competence or qualification.
adsagf
November 2017
Automatic Answer
While you wait for answers, we may have found some information which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix microwaves.