Alright, so I used this tutorial and after step 3 no my phone only boots up and says "Firmware upgrade encountered an issue. Please select recovery mode in Kies & try again"
So I tried installing the stock 4.4.2 and that didn't work, ended up with errors like Fused 3 > binary 1 and Something 2 > binary 1.
I should mention I got the Lollipop OTA update awhile ago, so I was all the way up to date. I'm guessing the issue here is that I'd need the stock image for the version I had before I started messing around, but as far as I can tell that's not available.
Not sure what to do here, but for now I'm completely cut off from communication so I could use some help!
I have the SM-G900A