Have you tried connecting to the commissioning web page of the FAP right
after performing the factory reset? (You need to connect to it directly via
Ethernet)
It is somewhat described in the section 5 of this document:
https://fccid.io/QGGIPA237C/User-Manual/User-manual-1470788
I use this process when configuring the FAP. (After that it pulls the
configuration from my ACS server)
If that doesn’t work, then I hope somebody other will help you :)