Device stuck after FRP was triggered

[Ned]

We have a handful of company devices, whose users were deleted before they were wiped.
We also have device that were factory reset from the bootloader itself.
We currently can not reuse these devices because the factory reset protection was triggered.

As an admin, I am able to login on the device, but I see only my general google account information, thus no way to wipe the device. 

In Company inventory I see the said devices, but it is shown as unassigned.
The question is if there a way to wipe these devices for a future reuse? 

[willem348343]

yes! if you search on youtube you can find some video that have a step by step guide on how you can exit the setup wizard (here you're stuck), install a administrator app, kill the setup wizard, clear the cache. Once you've done that you can setup the phone like you should 

something like this: https://www.youtube.com/watch?v=Pg0D4FO679U << but look for you own device. 
it takes a lot of time but it will work eventually

[Ned]

Seems like they do not work anymore. 
I can not enable installing apps from unknown sources, seems this was patched.

I will keep on looking, but if there is any other hints, tips etc. please share them.