Have I ruined my car?

I’ve just purchased a Mazda MX5 (NC1) 2.0 with rev limiter at 7,500. Today I’ve accidentally mis-shifted from 3rd gear to 2nd when I was red-lining on 3rd. I’ve immediately noticed the accident, clutched in and put on 4th, so the car over-revved just for a little.

Then, I drove for a couple more kilometers without any issue (apparently), but suddenly the “check engine” light turned on and after a while it automatically turned off. The point is that my car died by itself when I was slowing down for a red light and…it wasn’t able to start again.

From what I remember there were not weird smells nor noises.

I was a little low in engine oil and the battery was perhaps a little old.

Now I’m very upset, mechanics still do not know what and where the problem is.

What is your opinion about this?