My microwave won't heat. Everything else works fine.

History:

Loss power to PCB. Replaced thermal fuse. PCB now works but won't heat.

Tested all switches and thermal fuses. All tested fine. Tested all components and tested fine. Figured PCB relay was bad.

Replaced PCB with new board. When power was restored, microwave started working (heated water), and all fans running, but turntable didn't turn. All this without touching keypad or resetting clock. Only was to shut off was to unplug

Figured PCB was defect. Replaced PCB with another new board. Back to original situation. Everything runs but does not heat.

Stumped.

Can't figure what to do next. Any thoughts?