BIGSAMDA1st, can I call you "Sam?" Your post count would indicate you've got more experience than I do so I thought I'd ask: aren't all the Sprint S3s on the MK3 build by default? Or are there inconsistencies within the Sprint-branded line of S3s?
Oh man. At least you've still got access to the download console. Can you also access the recovery console? Also, sounds like you're new to rooting (I could be wrong, just going on your comment about certain techniques being too advanced for you to wrap your head around). If you're new, you really picked both one hell of a time and one hell of a phone to cut your teeth on. Samsung's official 4.3 update (which, for all I know, is shipped standard now) comes with the KNOX bootloader which is, in certain situations, basically a bomb designed to ruin your week... and your phone. In particular, it has a REALLY nasty reaction to attempts at downgrading to the old (and much happier) bootloader. It also seems to really hate the older versions of TriangleAway (might hate the new one too, for all I know. I won't touch it anymore). It has other ways to make you hate life as well, but those are two big ones.
How to tell if you have the KNOX bootloader: Did you install the official OTA update to 4.3? If so, you've got the bomb. Did your phone come with 4.3 right out of the box? If so, you've probably got the bomb. Are you still unsure? Look in your Download console for red text that says something like "Warranty Void Bit" or anything that mentions KNOX. If so, you guessed it, you've got the bomb.
If you have the Warranty Void thing listed, then check to see: is it a 0, or is it a 1? If it's a zero, don't do anything else with trying to flash your ROM or root the device until we try some things in your Recovery Console (assuming it's also accessible). Once that flag is tripped, there's no going back... Not a huge deal if it's just a personal device, assuming you're not still under warranty... If you are, well, don't trip that bugger if you can avoid it.
Sprint's Samsung Galaxy S3
Flashed to VZW prepaid unlimited
Android 4.3 (MK3), complete with KNOX set to 0x1 thanks to the OTA update it came with.
Use this link to sign up for Copy's Cloud Storage and we both get an extra 5gb (that means you start out with 20GB!)