What firmware version is it on? You'll need to get the firmware updated if it's not the latest. You'll have use the K4 jailbreak and the 2025 DevCerts as it's far too old for LanguageBreak. If you can't get it registered then it'll break when it goes on wifi unless you block it talking to Amazon.
Official Amazon firmware downloads
https://www.mobileread.com/forums/sh...d.php?t=225030