Hi,
Sorry to hear things didn't go better with that repair.
If your notebook was repaired recently, consider contacting your local ASUS support to find out your options since they should hopefully provide some resolution if you received your notebook in worse shape than before.
Alternatively, if you are in the U.S. and had problems with a previous rma, you can also email Jolene at
cl-jolene@asus.com as mentioned at this
thread to ask if she can help you keep an eye on your RMA if you decide to send it back again, but not sure which way will be better.
Anyway, hoping ASUS repair will be able to make this right the second time if you paid good money to fix it.
Also, be sure to provide clear concise details of how to catch the problem, or maybe include a copy of the benchmark that caused the shutdown problem for repair to check when they get your notebook and don't wait too long to contact ASUS repair if you think you may want to do this.
Good luck!