Default Did my phone just SDS?

I was running my phone perfectly fine, and when I turned off the phone to replace the battery, it won't turn back on at all. The Samsung logo just loops repeatedly, and I can't get into Recovery mode at all. I can get into download mode, (sort of), by the conventional means, but when I press volume up to confirm download mode, I can't do so. The phone hangs for a second, and then restarts its self. Is this SDS? How do I get it fixed? I am in the USA, and I have a SGS III i9300. My phone information is below in my signature.
Phone: Samsung SGS III International i9300
ROM: OmniROM Official NIGHTLY
Firmware: 4.4.4
Baseband: UBUGNF1
Bootloader: UBUGNE1
Kernel: 3.0.101 Boeffla-Kernel-2.4-beta5-Omnirom-NG-i9300-20140902@andip71 #1
O/C Level: 1600 MHz
Media Card: Samsung 64GB Class 10 MicroSDHC
Battery: 7000 mAh ZeroLemon