@fredldotme I've wiped it one more time, manually and after that the installation did not fail. Thanks a lot for the help.

Maybe I made some progress because now my install fails on

mount -a mount:mounting /dev/block/bootdevice/by-name/system on /system failed: Invalid argument 

https://paste.ubuntu.com//p/ZwZWvw7wB9/

Update:
After downloading Ubuntu 20.4 and running installer from the liveCD I got the same result.

@c4pp4 Yes my device can't be trusted anymore Good idea I will try the Ubuntu 20 approach.

@c4pp4 Yes, I did wipe the partitions as well.

@fredldotme Thanks I'll try to do with the installer as it is more than just doing stuff with abd shell and copyting files around.

This is my first attempt so sorry for dumb questions. Is there a way how to see the UB-installer logs without filing bug?

@c4pp4 Yes, I realized that later but what I am asking for now is if there is a way how to avoid using this graphical installer so I have clear logs and can find what is the issue and possibly find the solution.

Basically is there a list of the commands that the UB installer is running, TBH I don't want to spend time figuring it out from the async javascript code in the electron app.

I am hitting similar bug to https://github.com/ubports/ubports-installer/issues/1052 and thus I'd like to do a manual install but I am unable to find the instructions. Installing from linux box so I have all the unix tools at hand and I can read code too.