Appliance Repairs Job - Diep River, WC, 7800

Defy Microwave Convection Oven. Model DM0356. Microwave part does not work, but the oven and grill does. I have replaced the high voltage fuse inside, with the correct part from yebo Electronics, but it still doesn't work. The fuse has not blown again. So suspect the problem is elsewhere

How much to repair? Or must I bring it in for estimate? What is the estimate to have it fixed.