Any appliance is fixable !
To diagnose the fault / faulty part you will need :.....
a) electrical meter (multi meter)
b) megger 500vdc
the parts that normally fail are : antisurge fuse/capacitor/magnetron/diode/microswitches
If you are not sure how to carry out these tests
you should get a competent engineer (approx £30.00)
+ parts max repair £80.....regds, coolcat refrigeration
coolcat, March 2008