Typicaly if the light & turntable works or the fan & display (countdown) works, but the oven doesn't heat, it is most likely that because a door switch has gone bad.
Please make sure the replacement microswitch has been certified safe to use in household appliances, otherwise the switch can be a liability.
Contact Arrangement: SPST(Normally Open)
Insulation resistance: 100MΩMin
Contact resistance: 15mΩMax
Use temperature: -25℃ ~ +130℃
Operating Force: 200 gf Max
Release Force: 50 gf Min
Movement Differential: 0.4mm Max
Operation Position: 14.7±0.4mm
Please make sure the replacement microswitch has been certified safe to use in household appliances, otherwise the switch can be a liability.