PW3 Get jailbreak back after reset?

Hey Guys,

a few years ago I bought the Kindle PW3 and the first step was jailbreaking it.

I had no problems and everything was working fine.
After a lot of time not using the Kindle today I loaded and started it.
I noticed, that the Kindle upgraded to the Firmware 5.10.2 by itself.
I also recognized, that KUAL was not accesible anymore.

Then I made a huge mistake: I reseted the Kindle via the settings without knowing, that a downgrade from my Firmware is not possible.

Afterwards I tried to reinstall the Jailbreak again, which did not work.
The Kindle deletes the files by itself.

Is there any way to get the Jailbreak back to my device?

What is really interesting:
In the past I installed some custom screensavers.
Those are still (after the reset) working.
I remember, that I had to put the files in a folder named "screensavers" but this folder does not exist anymore after the reset.

Maybe the reset did not delete the Jailbreak?

I hope you can help me :)

Greetings