You are welcome , only sorry we were not able to find the problem.
I think you have just been unlucky and a part has failed. I always stress test a new build for stability. Given your computer tests freezes but does not shut down, I don't think it is a heat problem. Manual overclocking could have caused damage if a voltage setting was drastically wrong..
I would get the PSU tested first, then you know which way to go, depending on the result.
If you do have to take everything in for testing, put the rig back together, easier for them testing and safer for you transporting. Don't forget to also include the stock cooler.