The F6 error is indicating a stuck relay on the microwave control board.
Without knowing the age and frequency of usage,
It may just be a pitted contact on the relay, but usually they are soldered in place, and are not serviceable unless you are handy with a soldering iron and the safety factors with taking the metal shroud off a microwave.
sometimes... and this is sometimes...a good jarring will shake the contact loose.
I don;t know if this is a electro-mechanical relay or a solidstate relay... either way... if it sticks once, it will stick again...
Btw, I’m available to help over the phone in case u need at
https://www.6ya.com/expert/lisa_52daba487e5b4d53