Further down the thread … a bit like yours Install e/OS on Fairphone 6 - #51 by poog72 … he finds a solution a week later. A USB “check the full chain” issue [1] one might say.
The tail of your log tells what to do … unless this did not work, sorry you tried already 
ERROR: Please unplug the phone, take the battery out, boot the device into
ERROR: fastboot mode, and start this script again.
ERROR: (To get to fastboot mode, press Volume-Down and plug in the USB-C)
The script will be just fine from Fastboot mode. (fastbootD would / might allow to interfere or adjust but I think you should avoid … the script will aim to rewrite all needed partitions correctly.)
[1]