Hi, welcome to Just answer
If the microwave doesn't heat there are number of things that might have caused this issue, as the light is on and table rotates so it seems the door switch and thermal fuse are fine...from what you have described it seems that the high voltage transformer might be burned out. Microwave ovens produce a very high voltage in order to power the magnetron which emits the energy that cooks the food. When a high voltage transformer fails it will usually arch and have a burning smell.
As the problem is with HV unit, I won't recommend this as a DIY as it has a charge of more than 3,000 volts and the HV capacitor should be discharged before starting any repair...
sorry for the bad news but the cost of repair will be around £170+ repair charges
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