A few years ago I had a "just out of trade school propane tech" do a summer service on my "standing pilot light" heater to get ready for the "heating season".
I can do this myself, but it is included in my prepay purchase of a year's fuel plus at my age getting down and up is a PITA.
After the service, he couldn't get the pilot to relight and after several hours declared I needed a new valve.
He ordered and replaced the valve, still didn't work.
I asked him if he had checked the battery in the thermostat and he had no clue what I was talking about.
I informed him standing pilot heaters, despite the fact their fan won't run, are designed to still operate and heat without electricity and the thermostat required a AA battery.
Yes, that was the issue and I knew it was, which is why I got a new valve for free as my fuel company decided they were at fault and didn't want to cover the cost to put the old one back in.
This year for the service they sent an experienced tech out with the newly hired one, at least to my house

 

trade school tech? That should have been your first clue into what they know and don't about a propane system A propane certification is more or less the state and or feds requirement to simply handle propane, and it does require a brain to pass it as the testing is very strict..

And no I am no longer legally able to handle propane professionally but then I also pulled my Propane kit from the market a couple decades ago. To many customers that couldn't read an installation manual.