TWRP for Fairphone 3

Hey Hey.
First of All: THANKS to all of you for working so hard on solutions for the FP3 and helping people with issues. I really appreciate this, as I intend to use the FP3 with LOS.
I’m following the discussions on this forum for a time now, unfortunately I also have to write a post now…

I have (at least) soft bricked my FP3: It only boots into fastboot mode, I can’t enter recovery or fastboot boot the TWRP img and I am afraid I made a stupid mistake.
I originally followed pigpig’s thread about how to flash ROMs with GSI but the system directly went into a reboot cycle.
With the intention to do the process again, I downloaded the Fairphone_FP3_8901.2.A.0105.20191217_12171325_user_release-keys ZIP and tried to install it with TWRP to get back to stock. Unfortunately stock also didn’t exceed the rebooting cycle.
Next I wiped the phone with all all options checked – I’m sorry fo my stupidity – to be able to make a “clean” install and got where I am now. I didn’t know this would break the whole thing and I thought I can then use TWRP to install things…

Following pigpigs instructions in this thread I tried to flash all the partitions from k4y0z stock zip manually. But imgs like product, vendor and system are missing. Would I have needed to make a back up of them myself? :-/

I hope anyone can help me. If you need more information, just ask. I didn’t want to flood the thread with details.

best, Janos