First of all, there is no factory reset on photons anymore, or at least, there shouldn’t be: AVOID factory reset - What to do with unexpected LED behavior on a Photon
If you’ve got the CLI installed, try updating it by doing particle update while it’s in DFU mode. Then either try the app again, or the CLI in listening mode with particle serial wifi which should allow you to configure the credentials.
Doing particle identify should give you your device ID which you can use to claim your device.