I bought a Samsung Galaxy S3 I9300 about a month back from eBay. It was working fine till the last Tuesday, but after that my phone started rebooting by itself. My Galaxy S3 is powered by Android 4.0.4 and unfortunately I haven't enabled the USB Debugging Mode, nor have I flashed it with any custom roms. So, I can't flash with any custom roms, the solution suggested by most of the threads I have browsed through. My phone is also not going into the recovery mode. Please help!