RBS50 won't con't connect

Yes. For one thing, make sure you have no ethernet devices plugged into satellite 2 when you power it on and attempt to sync it to the router. That alone could cause you issues.

If that doesn't fix it, you can upgrade the firmware on the satellite by connecting directly to it with ethernet (or wifi, if you're able to). Since the satellite isn't connected to the router, it won't have any DHCP capabilities, so you may need to manually set the IP address on your computer in order to be able to do this. So, first go to the Netgear site and download the appropriate firmware file for your model Orbi, then connect to the satellite, go to the satellite's configuration page, log in, then go to the firmware page and manually update the firmware you just downloaded.

You can also go into the router's configuration and have it generate a new backhaul password, then try syncing satellite 2 (with no ethernet devices conected), then satellite 1. I don't think a factory reset with have it generate a new backhaul password.

I also don't know that it works, or even is supposed to, but you can also try connecting satellite 2 to the router via ethernet cable and see if they can get connected that way. If so, you might just be able to go to the router's config page and then have it either check for new firmware, or manually update satellite 2's firmware from there. Once you get it updated, then you could try syncing them again.