As mentioned above, you can reset Orbi using two methods. Well, this is the next one. In this method, you are required to access the web user interface of your device. Otherwise, you wouldn’t be able to get success with the Netgear Orbi factory reset process.
If you chose an Ethernet cable to connect your Netgear Orbi login and the existing modem, did you not check if it is free of damages or not? Probably not, otherwise, you wouldn’t be stuck in this mess.