They didn't explain the etymology. En panne means broken, not functioning. Dépanner means to remove something from that state, to fix it. A dépanneur is therefore a person or thing that fixes stuff, gets you out of trouble.
Dépanneuse == Tow truck
Il m'a dépanné en me prêtant vingt dollars. == He lent me $20 to help me out.
Ah la belle langue!
Dépanneur as convenience store could be a Quebec thing.
"Out of order" is something you see on a broken machine and not something to do with a shop!
One day, the AI kiddies will manage to work out how to stuff "Idia" into their wanky offerings. Until then, I'd rather read comments like yours.
Merci.
This phrase existed because the penne was a wood affixed to the mast of sailboat that allowed you to move the sail such that the boat slowed down and stopped.
That thing was called the penne because it looked like a pen (the writing instrument)
A tool that would dépanne you would be a tool that would do the job poorly but well enough for now. This is how the name is meant to be understood, a small store where you can buy like eggs, beer, milk, bread (it's a convenience store), maybe batteries, but not a full grocery store or pharmacy or tool place.