motor no longer goes on after switching off….

Hello first of all, I am happy driver of a ford escort 1997 combi 1.4liter injection. now I have a problem for some time now. if I turn it off, I have to wait a good 20 minutes until I can turn it on again. before he just does not start. battery new – temp sensor new reads. workshop, which has renewed the temp sensor as a problem (he probably wasn’t) I should scrap my car, because it would be too expensive to find the problem. I have now here read in the forum nest, but found nothing – suspected on “sprit not off” I can rule out. did the thing on made out, expanded, tested, installed, turned on etc….. does someone have a smart plan?? thank you