Sounds like the power button is switching due to the pressure. Short of sending it back...somehow can you prevent this by maybe shimming the case or something to keep the pressure from affecting the button?
I had this exact problem. It's a hardware problem. I brought my computer to a repair shop in Red Wing, MN, and they were able to diagnose the problem and fix my computer. The bad news is that it took seven weeks for the part to arrive, but the part was ordered straight from an MSI plant (China or Taiwan [not sure which one]) and it only costed $50 with tax (before labor). Just one little part! It may be your problem or not, but find a repair shop that will diagnose your computer. I had to pay for my diagnosis, but it was forwarded to the final cost of labor, which was lowered to $35 for the first hour of labor, and it didn't take more than an hour. The final cost after tax was just $85 for me.