That’s strange, when it showed that “Try again” message, Factory reset has always worked in my tests to bring it back.
The other partitions are flashed in a different format, and there is just no output in the script.
You can check META-INF/com/google/android/updater-script in the ZIP-file.
I’m not sure what is going on at this point, maybe @corvuscorax has an idea.
It should restore all the partitions to the original ones and boot without issues.
EDIT:
OK, I have another idea what might be going on, can you please go into adb shell in TWRP and do
ls -l /dev/block/bootdevice/by-name
send me the output please?