key in ignition on trying to start but does not crank!!! check engine light flashing rapidly!

Check your engine oil level. If it's to low your engine won't start. Start there and let us know.

I had this happen when our ignition barell went south. e had to wait a few days for the guys to get a new barrel and in the interim, he pulled out some parts so we could still use the car basically as if the car was hotwired. If we didnt have the real key in the ignition while starting it through the 'hotwired' part we had the same issue. It's to do with the key having a built in immobiliser so maybe your key's immobiliser is having issues?

I had the identical problem replace the starter relay perfect

Where is the light flashing? ..