1999 Mazda 626 starting intermittantly

My mom has 1999 Mazda 626. She can start the car up and drive it. Then if she shuts it off and tries to start it again it won’t. She says if she waits 15 mins it will start again. She has already had Battery replaced. She left it with the Mechanic for a week. Naturally it did not do it. I thought maybe a starter. Then after reading something on the net I remembered she had a big heavy key chain. Is it possible it is the ignition switch? Unfortunately I am 2000 mile away so I can’t look at it

If the engine cranks, don’t suspect the ignition switch, for now. The more information about what does, and doesn’t, happen when it doesn’t “start”, the more likely a diagnosis.
When the engine doesn’t start, does the engine crank? Let us know.

She should have had the mechanic DRIVE it for a week. Just sitting there with him poking around or looking at it didn’t accomplish anything. He probably started it once and let it idle til warm and restarted it …or made multiple starts in a short time. Not quite the same thing as being stranded and waiting 15minutes to start it again and going from there.

We don’t currently know if it’s an ignition issue where it cranks but won’t start …or a no crank condition.

Too my knowledge it won’t do anything when it doesn’t start. She turns the key and it won’t crank. She wasn’t sure if it clicked or not. The mechanic did say he drove it around. Also it has happened when the car has been warmed up. She may take a trip to the store for instance. When she comes out it won’t start then she waits as I said and it will start with no issues. It has happened my sister and he rhusband when they have driven it as well. My brother is taking it to his mechanic for a 2nd opinion.