Possibly some good news
So I have absolutely no experience whatsover with rooting anything, or any of that shennanigans, but I have just had the same problem, and here is what I did.
-Took it to an electronics shop. Apparently they often have loose connections, so tried to get that fixed up, they did that and it didn't work, so now they think it's the battery. This would have cost me $120 if it did work, which is more than i paid for the kindle second hand, but i didn't care bc I was going overseas in four days and I just wanted it to work.
-Called Amazon.If it's still within the warranty period then this is fine. They will just send you a new one, then you have 30 days to mail back the old one. If it's not under the warranty period, it will cost you $100 for the same deal. They replace it with a new model even if you have the old one which is nice, and they don't really look at them when they get them, so it shouldn't matter if it's been rooted/opened etc. The only thing is that you have to have actually registered the kindle with amazon at some point, which was a problem bc I bought mine already rooted. Also they only send to the US. Also a problem for me....
I realise that this may not have been the type of help you are looking for, but it's all I got.
