R9000 invalid serial number after factory reset

[augsy]

After factory reset, I entered the "serial number" from the router and the pop up says invalid.  Appreciate if someone can help solve the issue.

[plemans]

You shouldn't need the serial number. 

If you factory reset it, your default info is: 

login: admin

password: password

all lower case. you should be able to use that to log into it and change the loging password