In this case you see this on the screen: "to restart your phone press and hold the power and volume up buttons for 10 seconds."
OF COURSE you can get this fixed through warranty.
If you don't want to do that cause you don't want to wait, you can do what I did.
(I am not responsible if this doesn't work well for you and I guess that after this procedure they won't replace the button for free anymore)
1. Get a flat screwdriver. Heat it over stove, but not until it.s red, just until it is a little hot. It's better to heat it a little, try it, if it doesn't work heat a little more and so on. Otherwise, if it's too hot, when you touch the button it will melt everything around it and way too far into the button.
2. Put the screwdriver on some surface and keep it steady with the end sticking out. Hold the opposite side of the button a little pressed so that the part of the button that catches on the plastic sticks out.
3. Bring the phone towards the screwdriver carefully so that you melt that edge of the power button just a little bit. Just melt the edge, so you give it a slope like this / , not the entire side of the button.
Finally, you should get the same results as you can see in my pics. It's barely visible that the button has been tampered with and for me it's way better than waiting for weeks for the warranty to repair it.
Cheers and be careful not to get that screw driver too hot or too far into the button.
LE: be careful that the IR blaster is on the left side of the button, if you look at the phone from the front. In my case I had to melt the right side which is about 3/4 lengths away from the IR blaster. If you melt the side of the button that has the IR blaster in it, I'm not sure what would happen. The IR blaster should be fine, but the curvature of the button that you add by melting might deflect the light. Not sure.