Bought a house with Ring, need help connecting

I bought a house with multiple Ring devices - doorbell, base station, range extender, motion sensor, door contacts and keypad. Doorbell and base station are now active, but I can't get the range extender added to my network. I've tried factory resetting it, but after flashing rapidly, it does not start the startup mode as the website says it should. Any ideas how to get it to join my network? Any would this be why the chirping when a door is opened has quit suddenly?Door contacts and keypad also won't join. I haven't even tried the motion sensor yet.