PW5 My jailbroken PW5 auto update to 5.15.1. What can I do?

[S.Thanawat]

Hello, I'm not good in English but I'll try to give you most info.

As the title said, I just jailbreak my PW5(5.14.2) Install KUAL, Koreader use it normally. When it auto update to 15.14.3 I still can install Hotfix and KUAL again. In the KUAL menu I click Prevent OTA update every time.
Then today It's did auto update again, now it's update to 5.15.1 and I cannot do the Hotfix. After I copy the Hotfix file to root of my kindle and unplug it's show Update error something about wrong update file. I cannot click "Update Your Kindle" either, it just gray out. Then I tried to Reset, hope it could go back to 5.14.2 then I realize that's stupid thing to do still stuck with 5.15.1 and I think I've lost all my jailbreak.

Any option I could do now?