Combi Wave sage/breville microwave not heating

hi folks,
I got a combi from sage (oven/microwave/airfryer) is only 3yo and cost me an arm and a leg. it worked flawlessly till now (apart of being a terrible air fryer), then yesterday I used the oven for 1h (which I rarely use) and now the microwave is not heating up anything anymore.
The door closes fine, the settings are adjusted, the lights turn on, the plate is turning, and it makes the usual humming sound, but the food stays cold.
is there a fuse that I can change or some easy diy fix? I’m good at fixing things (not a pro), got a multimeter and a pair of gloves for working with electric stuff.
any help/direction is highly appreciated!

Brand: sage breville**
Model Number: the Combi Wave™ 3 in 1
Main Symptom: not heating
What happens & when:

Error Code (if any): none
Parts or tests already tried:
Photos / video link: