I'm absolutely a newer in this field,so i have to seek for help .

I recently get a Kindle 2,it is also known to be KT3. when i first connected wifi ,it soon began upgrading automatically, I agreed innocently.
Then disaster came! one day,i watched a pdf file in my kt3 but got a bad user experience.I started search for help.So jailbreak became my best choice.
but my firmware version is 5.9.2.0.1,is the latest version.I have tried every way.
1. downgrade:but kt3 does't recognize the special firmware at all.
when i use firmware fro amazon,it shows invalid updated file.
2. use jailbreak tool: in search bar ';installHtml' return nothing
I am thinking ,can i make a updated firmware,version is newer than 5.9.2.0.1,such as 5.9.3.0.1 which is actually 5.8.2 from amazon but not special. Then we may downgrade.but i don't know how to do.
please help me .Thank you!