Successfully rolled back to 3.2.8, then bricked after 5 minutes

Was rolling back my kindle fire hdx 7 3rd gen. Using this method, rolled back to 3.2.8. All good, no problems. Then tried to download the firmware to go to 4.5.2, some reason my laptop kept stopping the download partway through, so I tried to download on the tablet, battery was about 40%, download for 4.5.2 was 20% or so. I leave it alone for five minutes and come back and it won't turn on. I tried charging it for bout half an hour, tried resetting it by holding it for 30 seconds, no luck. I plug it into the computer, it shows up as QHSUSB_BULK, tried updating drivers and it can't find anything. I'm at a loss for what to do, I can't find the box for it in case I need to turn it in for another one, I believe it's still under warranty. So my only hope is to somehow unbrick it. Any help would be appreciated.