Kindle fire 2 red screen. help please

[AshtonCable]

I have a kindle fire 2 and I thought it was a 1st gen because when I bought it on eBay it was advertised as that.
So I stupidly tried to flash a kindle fire 1st gen recovery and bootloader from a root app, because I was having trouble getting into fastboot mode. I now have a fastboot cable that my dad made for me (because I dont know how to use a soldering iron). But I still can't get it to go into fastboot mode, it just goes to the red screen after showing the kindle fire logo for half a second.
I would really appreciate some help because i'd really like to get it working.

 

[Dapostrophus]

I also have a Kindle Fire that I was confused about whether it was first or second generation. Everything mentions software version 6.x.x, but I couldn't find anything like that. Mine was running 10.5.1. I'm not 100% sure that's the right software version I was looking at. Anyway, it kept coming up as Otter-something in my device manager, and I finally found something saying Otter was 1st gen, and Blaze was 2nd gen. Then I installed the TWRP app, I think, to flash TWRP after I had it rooted, and it kept coming up saying it was Blaze. I can't remember what else, but I had multiple indicators suggesting it was 1st gen, and the same for 2nd gen. So since that app said Blaze, I flashed the Blaze TWRP file, and now it just boots to a red screen.

I do have a fastboot cable, and it boots up to the Fastboot traffic light screen, but if I try to run fastboot on my PC, I just get "waiting for device." I've looked at tons of guides that say "make sure blah blah in Android SDK." Am I right in thinking Android SDK has been replaced by Android studio? If so, how the hell do you do whatever they're telling you to do in Android Studio? Because I can't figure it out.

Any insight anyone can offer would be most appreciated.