Replicant

Hi

I do have:
Phone: Galaxy S 3 (GT-I9300)
Android version: 6.0.1
Replicant version: replicant-6.0

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I) I have tried to do:
1. #adb reboot recovery #go to recovery mode (sucess)
2. navigate apply update # in replicant recovery
3. I have tried all following (but unfortunately same result):
#adb sideload l replicant-6.0-0004-rc5-transition-i9300.zip # failed with:failed to verify whole-file signature
#adb sideload l replicant-6.0-0004-transition-i9300.zip # failed with:failed to verify whole-file signature
#adb sideload l replicant-6.0-0004-i9300.zip # failed with:failed to verify whole-file signature
#adb sideload l replicant-6.0-i9300.zip #This one works though (6.0 0003)
4. after whole restart of phone, when in normal mode i have tried:
5. #adb root
6. #adb disable-verity
7. reapeat points 1-3 with same result

II) So I have tried to goto bootloader and replace replicant recovery with anything else but there is no response from device since iam in bootloader.

1.) I have tried to perform also something like: #heimdall flash --RECOVERY twrp-3.2.3-0-i9300.img --no-reboot
But the respone i got is stomething like: "ERROR: Failed to detect compatible download-mode device."

2.) dmesg after reboot to bootloader gives only: "usb 7-1: USB disconnect, device number 16".

3.) I have tried also to add udev rules (/etc/udev/rules.d/99-android.rules) where but no sucess:
SUBSYSTEM=="usb", ATTRS{idVendor}=="18d1", MODE="0666", GROUP="plugdev"
SUBSYSTEM=="usb", ATTRS{idVendor}=="04e8", MODE="0666", GROUP="plugdev"

I have tried retart computer after rules were updated as well.

- How could I upgrade recovery when in bootloader device become just silent
- I have read [[https://redmine.replicant.us/projects/replicant/wiki/AndroidSystemKeyMigration]] where there is written:
"We wrote a tool to create a migration script that can be generated from various data (certificates from previous releases, a running image, etc) so that users running custom builds could also migrate back and forth between different images."
Is that migration script anything that might be useful in my scenario, if yes any more info about that?
- Any idea howto overcome "failed with:failed to verify whole-file signature"?

Anything goes
Thanks
R.