Most of the time we do not recommend DIY repairs on microwaves as they can really harm you. I understand that this one is really not a throw away at $2500. http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SpecPage&Sku=JTP90DPBB
Unfortunately the warranty is only 1 year. I would venture a gues and say that this unit uses two 120 volt circuits. Check your electrical breaker box (actually throw the switches to reset them), to see if you are getting power to just onje side.