Sorry but this sounded like a warranty issue and my thought is to try the old reset procedure. That is just like we do on laptops over in the CNET Laptop Troubleshooting system. But it's well inside the warranty and its dead.
i bought a galaxy R about two months ago. i used to have the common problems like no audio in calls or switch off once in a while. and found online that it is common in this phone! today i was using it put it in my pocket went out n got back home. i pull it out to make a call and it is off. and i have tried almost all that i can to turn it on but no use. battery was more than 80%. some one please help, i cant take it to service centre and wait days together.