My experience with a BMW 330xi a few years ago might help here…
My brother’s car - he had a repair he did (don’t remember what exactly), and he couldn’t restart the car. Fast crank, good battery and starter, but it would never catch. Starting fluid wouldn’t even take. So I went to the BMW owner’s forums and did some searching.
Turns out what was going on was the repeated start attempts would wash down the cylinders and prevent good compression. The fix? Pull the spark plugs. Put some sort of oil (not a lot!) into each cylinder, replace the spark plugs, then try to start.
It worked on that car, and it wasn’t worse for wear. We did change the oil soon after, what with all the gasoline that was likely in it.
Worth a try… 😎