PW I can't do any update on my Kindle PW1

[Sohaib]

I have a Kindle Paperwhite 1st generation (EY21).
A long time ago, I downgraded it from firmware 5.6.1.1 to 5.3.3 in order to jailbreak it.
Later on, the KUAL launcher expired, and I tried to install a newer version (copy/paste) and then install the new Keystore, but the KUAL launcher kept saying: “This item is not signed by an authorized developer.”

So, I tried to reset my device and re-jailbreak it, and the process was completed without problems, but KUAL kept notifying me with the same message.
Then I tried to reinstall the stock firmware, and I found that even though “Update your Kindle” was activated and the device rebooted, the firmware did not update and the bin file still remained in the root of the internal storage.

I tried the long-press power button method, and I also tried to install the update using an old MRPI, because it worked after resetting my device (since the time on my Kindle is not updated as I don’t activate Wi-Fi), but nothing worked and MRPI destroyed the bin file before rebooting.

I tried downloading the bin file again without using a download manager, but nothing changed. Even other bin files like the K5 Keystore update bin file would not install, and I found them still in the root storage after the device reboot.

I also tried the rename OTA method, but nothing changed.

At this point, I don’t know what else to try. Could someone please guide me on how to fix this issue or explain why my Kindle refuses to update or install the necessary files? Any advice would be greatly appreciated.