I installed TWRP and booted into it and got this
https://drfone.wondershare.com/images/article/2017/07/factory-reset-protection-3-6.jpg but I could not install supersu.zip to root phone. Later I rebooted phone and tried to enter TWRP again but got message that custom binary is blocked by FRP. What wrong have I done?
What you got here is actually the STOCK recovery. So this means the install of TWRP failed.
Furthermore, the phone detected that you flashed something and locked to prevent "suspicious activity" like this.
FRP lock is the basic protection of Google to prevent somebody to flash something (system, recovery...) to overwrite your actual system and break into the phone.
To get out of this mode the only way I see (because I got stuck in this situation also) is to reflash the system with your STOCK (basical) firmware.
Do it near of your home, maybe it's because you performed the flash away of where you go usually that your phone triggered FRP lock (or for other reasons, I don't know that much about the FRP security...)
If the reflash of your stock firmware fail (this should not be the case) then I'm sorry but you'll maybe have to reset your phone to get it back to its functionnal state...
But, don't go too fast. First perform the reflash of your stock rom.
Then if you succeed, check if OEM unlock were effectively on (that may be the trick) and you should also manage to unlink your Google account from your phone not to be bothered by the fu... FRP lock again.
