My steps was.


1. I received kindle with 5.6.5
2. Downgraded it to factory.
3. Installed JB and hotfix. Updated to 5.8.10
5. Installed KUAL etc.
6. Did reset(pushed Reset Device button) after a week or so.
7. Installed Update_jailbreak_hotfix_1.14_5.8.10_install.bin with no problem
8. Installed KUAL etc.
9. Did reset(pushed Reset Device button) after a while. Maybe 2 weeks.
10. Tried to install Update_jailbreak_hotfix_1.14_5.8.10_install.bin again, Update Your Kindle is greyed out.

My firmware now is 5.8.10(3202090019)
My first six characters of the serial number are B05409