Since when has anyone in history offered a warranty on a second hand
ecu tuned by god knows who thrown straight into a car without check?
Unless that was the specific advice given?
If it was tuned in Japan than it would of been full of timing (as they almost always are) leading to ping no doubt.
By the time you heard the first rattle it was all over, so dont feel bad about grinding it into the ground.
And no, its not bad luck. It is bad decisions diluted with mis information and lack of research.