Just to mention it:

Updated a Sony Z3c running and upgraded a tablet running . Thanks for all the people who build these systems!

It took me about two hours to

  • get the backup on the Sony working in twrp with a sdcard
  • do full system backups
  • update CarbonROM manually, because the reboot into recovery doesn't work
  • getting a stable usb connection to the tablet by rotating ports, cables and orientations of the plugs
  • install a newer version of recovery.img on the tablet
    • needed to recap how this is done in Linux using heimdall
  • install the newer LineageOS via adb sideload

Looking back at the process I prefer much upgrading my and I need to get back to the idea of getting a to get rid of the dependency on the LineageOS tablet.