MacBook Wont Turn On

I have a MacBook Air, just over a year old.

It was working fine then suddenly stopped turning on. No response to any commands, only the green light upon charge works.

I took it to the Mac Store, waited over a week before they called back saying there was 'nothing wrong' and that after 'running some codes' it started up.

Brought it home, plugged it in to charge, tried to turn it on.

Exactly the same.

Still completely inactive aside from the green light.

Wondering if there are any codes I can personally run or if I have to take it back.

Thank you for any help 🙂