KT2 Quick Fix for "This device is not authorized as a test Kindle"

EDIT: ('・ω・')Thanks to knc1 and NiLuJe, now I figure out that the actually useful operation I did was just restarting my Kindle. However when I tried to find a quick fix for this error, all I got was "reinstall the mkk". So I'll keep this thread here to help someone like me.

Hello everyone, I am not sure whether my experience can provide you any help or inspirations but I guess it should be better to share it here.

I had my KT2 jailbroken with firmware 5.6.5, and then I upgraded to 5.7.2. However, because I have different Amazon accounts, so I deregistered for using another account. No doubt I got the error "This device is not authorized as a test Kindle by the developer of this item". Because I only have KUAL installed without any extensions, and 5.7.2 blocked install bins through "Update Your Kindle", so I actually cannot do anything. Even diags mode requires access command line on KT2.

However, I noticed that, those bin files on root directory seems deleted directly by the system after I ejected Kindle from my computer. So I tried to transfer the JailBreak-1.14.N-FW-5.x-hotfix bin file via USB cable and press power button for a while to reboot the Kindle immidiately. It works! Now I get my KUAL back!

So, good luck, hopefully I can help anyone here.